I just finished a game in which I was just managing to keep on top of the other races' progression, when suddenly in the course of less than half a year 5 of the 9 races surrendered to one of the other races. How lame is that?
I specifically started with all "rare" settings (habitable, stars and planets) and 9 races so that there would not be a "colonization rush".
If the only way the AI can possibly manage to win a game is to have all the races surrender to one other one, this game just isn't worth playing any more. This is the cheese tactic to beat all cheese tactics.