I just made sure my gamesas.com and gamespy account had same e-mail and password.
It's true that whatever accountname you've created on gamesas.com can't be used in-game, it's "taken" according to Crytek's system. And they'll of course have to fix that.
I then went to create a new account IN GAME, same mail as gamesas.com and gamespy, same password too and it worked!
Jeez.
I still want "DarthLazze" back to play in Crysis 2 MP, but for now I'm on "Pwnchap".
to Crytek: Despite the account mess, it's a beautiful game you've created. Looks wonderful, good gameplay so far.