I think it's not going to happen until the new graphics engine is patched into the sim and somehow it even makes sense that way.
I mean, why go to all the trouble of contacting nVidia/Ati and spending valuable time trying to get their ear (as they will invariably pay more attention to other titles) when the entire graphics engine is being redone?
We're well into the minimum time frame specified by the developers for the new graphics engine reaching beta stage (they said minimum two weeks for beta, plus a week minimum of testing before the patch goes live, we're in the third week currently), we all know deadlines tend to slip by at times, so let's just make a moderate assumption with a nice, big error margin and say that the new graphics engine will be here in a month from now.
Well, it might take as much as or more than a month of back and forth correspondence to get nVidia/Ati to release SLI/Crossfire profiles, then waiting for the next driver release that will include them. In other words, by the time the profiles are here they may be obsolete due to the new graphics engine.
I know it's hard to wait at times, but seeing how the sim is nicely flyable on my two year old PC with a single GPU, what i would do if i was using SLI/Crossfire would be to make a custom profile that disables one of my GPUs when running CoD, turn down a couple of settings and fly in the meantime. I've been recently getting another urge to dive deeper into how stuff works in the sim, so i moved from fighters to bombers and have been having a blast the last couple of days.
Making a couple of very simple practice missions in the FMB, letting the AI fly them to test things out, then flying them myself to do some bombing practice, fiddling with the bigger, more complicated aircraft...it all helps pass the time very nicely until the patch arrives