If you thought Valve's switch from Internet Explorer to WebKit for its new beta version of digital distribution platform Steam — or the semi-irrefutable hints of OSX compatibility within — were just coincidence, this morning's latest viral blast should seal the deal.

Just days after ramping up a fantastic campaign hinting at new developments with their Portal, the developer let loose a set of images sent not only to games press like RockPaperShotgun and Eurogamer, but MacRumors, as well. With an Apple-logo-emblazoned Gordon Freeman, iPod-ad-silhouetted Team Fortress 2 Heavy, and John Hodgman/Justin Long dual-turret montage, the message is pretty clear.

Below is a hi-res collection of all the images released thus far. With their iPhone-esque "dot" navigation at the bottom of each image, there seems to be just one more to go [UPDATE: MacWorld got the final image of Half-Life's Alyx disrupting a version of Apple's classic 1984 ad], and with just days to go to the 2010 Game Developers Conference, we're likely less than a week away from their grand finale.