June 19, 2007 - Multiple Xbox 360 achievement sites posted the hottest list on this or any other planet today. Halo 3's 49 achievements (for a total of 1000 Gamerpoints) were revealed by achieve360points.com, among others.
A few things can be gathered from the achievements (oddly enough, none of which are secret). For one thing, these aren't final. At least, the descriptors are not, because some of the achievements have placeholders on scoring requirements. We also now know there are nine chapters in the campaign. And the skulls are back. In Halo 2, a skull was hidden in almost every level. Finding it was sometimes tough. Sometimes a skull in Halo 2 unlocked abilities; now it unlocks achievements.
When asked to confirm the validity of the list, a Microsoft representative said: "Halo 3 is still in development and achievements are not final."
Spoiler for Achievements on Halo 3: