Kotaku reports that Valve may be preparing a version of Steam for Apple computers based on data found by forum members who use the digital game download service.  Valve launched an open beta to an updated Steam earlier this week.  Steam forum members have since found files for Mac operating systems in the updated version.  The outlet says while the existence of some Mac files could be related to Steam’s new interface using WebKit, there are files specific to Mac OS X graphics and menus.  Read more at Kotaku.