If you hadn't heard, Valve is expected to announce Portal 2 this Tuesday at GDC. GameInformer's upcoming cover story on the new game leaked over the weekend, and the helpful folks at the Portal Wiki scanned and transcribed it.
The whole article is worth reading, so I won't summarize it here. But I will point out one interesting detail: the the list of launch platforms on the first page of the article includes the Mac, confirming what you already knew if you've been following Valve's recent teaser campaign. Even so, let's take a step back and ponder this: Portal 2 is a major game from a big-time developer, and it will have Mac support on day one.
Of course, "Mac support" can mean a lot of things. EA has been selling "Mac-compatible" versions of its games on launch day for years. But they cheat: their Mac versions are in fact just the Windows versions running in an emulator.
But Valve is a company known for making quality products. Emulated Windows games are adequate at best, and I just don't see Valve shipping something that's just adequate.