The adapter in the USA comes with a free game (Frequency - Cool music game) and a coupon for Twisted Metal: Online.
Sony know how popular Twisted Metal Black was and giving an online version away free would result in many people immediately buying the adapter. Hell its practically the same game as Black but with online play so it really wouldnt have cost too much to make.
Eithe way, TMB is one of the best multiplayer games ever, and TMB: O is going to be.........awwwww yeah