Details of what aren't specific, but big-time PC game vendor Valve has thrown their hat into Mac development. The game maker is probably best known for Half-Life and Left 4 Dead, in addition to the company's Steam. It appears at least Steam will become available for the Mac, although what titles will be for the Mac OS is yet to be seen. Steam probably could be best described as the iTunes app store for PC games. It essentially offers games for sale and instant download, and a method for facilitating updates.
The announcement came in the form of six Mac-centric teasers sent to six different Mac and gaming websites. MacRumors has a listing of the teasers.
The move is big news for Mac gaming, but it will be interesting to not only see what will be released, but what will be the reception. Mac gaming is lags considerably from PC gaming, which itself is arguable (not really) shadowed by console gaming. Mac gamers are pretty accustomed to getting titles years after initial release, and perhaps even turning to the iPhone OS for their gaming.