It would obviously be the GTX 480 SLI setup. Keep in mind that those things are flaming devils, eating power and spewing off heat and noise at levels that have yet to be matched. That said at $220 a pop you get considerable performance. But seriously. Have a strong power supply and even stronger airflow.
The noise factor is going to be so high for the 480 SLI option that its worth it to get the 560 Ti's in SLI instead. They are very close in performance, but the 560's are much, much easier to live with (coming from a former GTX 480 owner).
Well, if you can wait, then a single 680 is perfect for you. If you can't wait, then I agree with everyone else with dual 560TI's. Cost/performance/noise is unmatched and will last you along time.
One thing to keep in mind if vram. 1gig is fine for now, but once you start adding in all that sampling and move to a higher resolution, you need much more than 1gig for you games to be smooth. And no, you don't get double the vram with 2 cards, you only have 1 cards worth available. See if you can find 2 gig 560 Ti's.
Playing BF3, maxing it out becomes a matter of having enough VRAM. A 3GB GTX 580 SC will be just fine for the job. and Won't use as much power thus cutting heat down a bit. Idk if you were going for the look or just want the best performance.... But if you can suff it... The GTX 680 is the best option you can get right now. Has plenty of vram.
1080p: GTX 580 3Gb or GTX 680... getting two cards may not give you the Vram you need. I mean a GTX 580 regular at just one monitor might.....
The ROG Matrix GTX 580 is 350 or so last time i checks. or you can grab a 2gb GTX 570 for a good deal
recon-uk is on to something there. If you don't mind the heat or noise they output, then dual 480's in sli are impossible to beat bang for buck. I still prefer the single 680 option, but availability is a problem.
If you do get dual 480's, just keep them properly cooled and they should do you just fine.