Bioshock is actually currently 4th all time on gamerankings:
1. The Legend of Zelda: Ocarina of Time 97.7%
2. Soul Calibur 96.4%
3. Metroid Prime 96.3%
4. BioShock 96.1%
5. Resident Evil 4 (GC) 95.8%
The Edge review has yet to be applied to it's listing. When it is, the game will drop to 5th below Resident Evil 4, with a score of 95.7%. This wager is certainly not over for Metroid Prime 3. For a while there it was looking like Bioshock had it won without any competition, but MP3 could really give it a run for it's money.
http://gamerankings.com/itemrankings/simpleratings.asp?itemname=