Gamers tend to remember good games better than movie critics remember good movies. Most "best picture" candidates are released in Nov-Dec because Academy members (average age of 85 or so) have too short a memory to nominate an awesome pic from 10 months earlier. But gamers have never had much trouble with that - remember RE4 was an early year release, too. That means ME2 is definately a candidate for GOTY.
HOWEVER...
The industries biggest season is in Nov-Dec. Most studios plan to release their very best games at that time in order to maximize sales (another way games differ from films - people actually buy most of the GOTY candidates, were most Best Picture flicks struggle to find an audience). That means there will be a ton of great games coming out to compete with it. Hell, just the prospect of new Metroid, Mario and Zelda from Nintendo