The news is a few hours old now: Valve recently distributed mock ads that, if anything else, implies that Steam will be available for Mac OS X.
Valve’s Steam is a popular online store for games. Customers browse the catalog of popular PC games—which includes recent hits like Modern Warfare 2 to DOS classics like Indiana Jones and the Fate of Atlantis—through a browser or the Steam desktop client. Games are playable once paid for with a credit card or PayPal, and after the desktop client has downloaded the content. No need to keep a game disc...