SLI works fine for me...
I'd like to know what nvidia settings you are running. Whenever I set it to SLI, everytime I warp my screen goes crazy. Seems to do it only with the 'Warp' animation, not teleports (odd that). Also, I get some mad crazy lighting effects on certain things. Namely teleport crystals and whatnot.
I'm using the latest drivers for GTX460 cards too.