Now, just when you think Steam might be the epitome of all things evil in the world of DRM, they go and do something like this. Buy a game once and you are able to play it on both Win and Mac? Not only is that genius, but it is something that should have been the industry standard from the beginning. In the past, some games would come in a "hybrid installation" format that included both the Win and Mac (and sometimes Linux) version on the same disk, but they were rarities to say the least. Now Valve will make it their personal standard... I hope this is stunningly successful for them so that other publishers/devs will learn to follow suit.

I agree with all the Steam bashing that goes on (which I partly agree with) I think they deserve a hearty pat on the back for this. Throws down the gauntlet for other publishers which I hope will be picked up by a few. I don't even own a Mac!

This is definitely a good thing, giving Mac users (hi brothers/sisters!) access to the great library of games available on Steam. I'm pretty sure though that it'll for the most part not be real ports, but instead the Windows binaries run through Cider or a similar Wine-related app, possibly making real ports even more scarce than they already are. Also, I find the line "allows a gamer playing on their work PC " almost more amusing - surely that depends more on workplace policies?

I wonder if this means that the dosbox games sold on steam will be sold using osx port of dos box. And i can see the torrents of users complaining about the wolfenstine 3d being sold is not the mac version that had better res graphics and worse game play. the mac port was build by interplay using the snes port as a base. i saw that storm when id did the itouch port pc users liked it mac users hated the use of pc sprites and wanted the mac sprites the current version uses mac wall weapon, and treasure sprites while using cleaned up pc sprites for the nazis since the mac ones are cardboard cutouts.

It is unfortunate that Mac users are stuck with the uninspired OpenGL. Direct3D 9/10/11 is a better API for developers and users.
Even though Microsoft cares little for PC gaming when compared to its XBOX unit, Direct3D alone is probably enough to lock Windows as the dominant PC gaming OS for many years. I assume that the next XBOX will use Direct3D 11 or 12, and since very few console games use OpenGL (PS3 supports it, but it is inefficient so it is rarely used), developers will have little incentive to use the troubled API.
While this announcement must be satisfying to Apple fans, I doubt that much will change in the world of Mac gaming, at least until Apple demonstrates an interest in it.

Here here!
I am also not a Mac user, but this is HUGE news for Mac users and good news for PC users too. Knowing that when you buy a game, you can use it on both systems is just great.

Well, that is not entirely true. I would estimate that 90%+ of all PC games are Direct3D-only, which means that in the vast majority of cases, you aren't getting multiplatform access.

In fairness the only games confirmed so far are Valve games and specifically the Source engine games. They have only said that their partners are excited about the possibility.

^ I suppose I should add the caveat that the game must have cross-platform compatibility.
I think the fact that this exists now could mean we will be seeing a lot more cross-platform compatibility now though.

Did you read the statement posted one page back? Valve is making all of their games fully native compatible with both Windows and Mac, starting in the development stages of the game, so it won't even be a port to Mac from here on out. Other publishers will eventually follow suit, or as was already mentioned, start using a wrapper like Cider to make their games Mac compatible. I'm sure at first most games will not have both the Mac and Win version, but eventually they will.

Why? Developers have snubbed the Mac before because the Mac gaming market is too small to justify the additional investment in porting a game engine to OpenGL. How will this change that? EA and Blizzard have supported the Mac in the past (EA with its mainstream titles, namely), and will continue to do so. Other developers may not see enough money in Mac gaming. If developers worry that PC gaming isn't lucrative enough, why would they put in more effort to develop for less than 10% of that market?

Nonsense. Blizzard has supported Mac OS for ages and other developers have failed to do the same. Valve's support of the platform will not sway money-conscious publishers. Multiplatform games must support 2.5 APIs: Direct3D (XBOX), PS3's native API, and a slight modification for Direct3D on the PC. Why would publishers want to shell out additional money to support OpenGL as well, when the returns would be so low? Cider is a joke. You can't run cutting-edge games in a wrapper and expect anything short of terrible performance.

I think you are being overly cynical and are perhaps slightly misinformed. I agree, Cider is a joke, however, it is one of the main ways already used to "port" to the Mac, most notably EA recently used it with the release of Spore. As for the reliance on Direct3D, it is not actually as hard as you think to switch to an OpenGL platform. Most commercial game engines already support both, even if only one is most frequently used. Even on Windows it can be as simple as altering a config file to switch between Direct3D and OpenGL. The problem actually lies in the game's main executable, not the graphics API used. In perfect world, all it would require is recompiling the executable against Mac dependencies to create a Mac compatible binary, but in reality, it will probably be much more complicated than that. Even with that complication, it would not require a very significant investment of time or money to get most games running on a Mac. There will of course be exceptions, but they will not be as numerous as you seem to think. This is part of what has always been so frustrating about the fact that gaming is virtually restricted to Windows: it really isn't that hard to make them cross-platform to begin with, so why didn't they do that?

My so-called cynicism is the realistic outlook applied by publishers. I disagree with you regarding your arguments on the technical elements of engine porting (OpenGL rendering support is not available on most modern PC-only games, you may be recalling games from the GoldSrc era when such cross-compatibility was common).
Regardless, if you believe that porting a single program to the Mac will change the ongoing reality that Macs are snubbed by most publishers and developers (for reasons upon which we do not agree), I respectfully declare said belief misinformed.
Blizzard's longtime support of the Mac has had little influence. EA's release of mainstream titles on the Mac has not influenced the likes of Activision, Ubisoft, or THQ. Some companies cared about the Mac before this announcement, and others did not. As an executive at a major publishing house that has previously discounted Macs as a viable market, would the release of Steam on Mac OS really sway you? Would it change any of your reasons for having previously refused to release games with Mac OS support?

The largest digital distribution service for games on the internet adds Mac support for both the client and all of its parent company's games... that is hugely influential. More so than any single publisher or dev casually and quite quietly supporting the Mac would be. Absolutely it would sway me, or at least make me look twice at the possibility of publishing Mac titles. Looking twice might be all that is needed to change things for the better.

If you believe that such is the case, as a PC gamer, do you find it encouraging or discouraging that Valve and other developers will be spreading their already limited QA and support resources to another platform?