There is a new game called "Homefront" coming out in two months.
The one thing that makes the potential for this game in being one of the best FPSes ever (for singleplayer) is that the campaign story-line was created by none other than John Milius, the man who was the main screenplay writer for Apocalypse Now, one of the best war movies ever made.
You can find the trailer under "videos" at the link, which I find to be an amazing trailer. The use of real-life clips to incorporate the story-line for a possible future is something I haven't seen done before so well.
I'm buying this game.. I think we all should.