Take it with a grain of salt. GameSpot aka Ca$hWhore newsletter that I subscribe to has a release date of Dec. 31, 2009. However, their website for Diablo III info has a release date of TBA.
any kind of release date you see from anywhere but the official source, is all a guess, Like i said before, i been hearing rumors (from friends of mine who work in the industry) that it might be around this Christmas, cause they have been workin on this game for the past 3-4 years. But again its all rumors till an official announcement is made!