
If you check out xbox360achievements.org you can see the final achievement list for Splinter Cell: Double Agent. Perhaps, this can hold you over until the games release? Just stare at it... in all its glory.
What is missing from the list? A leaderboard achievement. Finally! Older, casual gamers, do not have to strive for the impossible! This, by far, is the best lack of achievement in the entire list.
Solo mode seems to be the place to capture the most achievments in Splinter Cell. That may or may not be good for those multi-player gamers out there. This might be due to the "stealth" type gaming style which is the theme of the game. Gaining achievements "as a group" may not be the correct direction to take the game if it revolves highly around "stealth."
Oddly, completing the two training courses will net you 40GP which is the same amount you will receive for completing the game, in solo, on hard (called "The Professional Ninja"). Most of the achievements, however, are all under 30GP with a few exceptions for the harder ones (40GP-45GP).
This game contains "secret achievements," something developers have been doing since launch (Kameo had some of these). One Double Agent secret achievement lists 100GP for completion. Given the game contains 40GP for beating it on hard one can only assume this will be a very difficult achievement to obtain (hopefully not a leaderboard achievment!).
For those itching to own this game and have a serious addiction to Xbox 360 achievements, take a look at what the future holds for you.
Full list: xbox360achievements.org