Steam game on another account

Can my friend play my game on his steam account on my computer and my savegame won't be deleted? (for example: MW2 and BFBC2)

No not possible, once the game has been activated it can only be used on the one account

ok thanks dude.

so based on what I have read it is true that the dickheads at steam have incorporated a way to monitor the use of the game so that I can't give a steam game that I have played to my son to play. Basically it is one play and you are done. No way to give or share a steam game with anyone else. I hate steam!!!!!!!!!!!!!!!!!!!!!!