Valve software, which ported its Steam downloaded-game service and its Source graphics library to the Mac, chose to use native code rather than emulation to solve the port problem. Native code makes a certain sense. Steam includes WebKit, and Source depends on OpenGL. Game developers leveraging Valve's technology will be able to support Apple's platforms as well, though such support may not be automatic.
"Steam Play" will allow users to start and stop games on Macs and users of Microsoft's operating systems, users will be able to share servers and "lobbies" between players using either platform, and performance is expected to be comparable between the platforms.
With Apple's portables becoming a major game platform, the conversion of the actual desktop hardware into a "tier-1 platform" – in the words of Steam development director John Cook – is an interesting but entertaining occurrence. Whether it helps mainstream Macs, or reflects that Macs have become mainstream, may remain open for debate.
Booting into MS-Windows for games may be a thing of the past.