it isn't pointless because the price will come down it isn't that expensive to get two 6800GTs anyways - about £600
Yeah for THOSE cards dude, they won't be around forever, when those cards die down, they won't be enough to play the top end games (of course this won't be happening tomorrow, but it's just an example) then more $1000 card sets will come out.
As it is you can max out everything on most games with a 6800GT or something like the X800XTPE or X850XT and things like that.
SLI is bragging rights more than it is performance. It won't last. Especially with Cell technology around the corner