Valve's making it look pretty evident that their Steam platform is heading to Apple computers. A number of websites have been sent promotional images, all containing characters from Valve developed games, all parodying Apple's various ads in one way or another.
With GDC coming up, that's likely when Valve will spill the beans on the announcement they're teasing. Valve may very well launch Steam for Mac, alongside Mac-enabled versions of their games, which is a likely case considering Portal, Left 4 Dead, Team Fortress 2, and Half-Life 2 are used in the parody images. Launching with that line-up may very well entice other developers to get their games on Steam for Mac, and not to mention get the attentional of all the PC-game-starved Mac owners out there.
Check out some of the images below.