Ubuntnu 12.04 or 12.10? 12.04 has drivers that support the GTX 680...just. Its a farily early revision. 12.10 has a newer driver version.
I assume that you are buying a card like that for gaming. I wouldnt be paying $470 for a GTX 680, the performance difference between it and the GTX 660 Ti (which is about 2/3s the cost) isnt big enough to make the GTX 680 worth it IMO.
The GTX 680 also draws more power than the GTx 660 Ti and outputs more heat.