Many people still play games, even the newest ones, on DX9. I would consider DX11 a perk, but not a deal breaker. Time could prove me wrong, but it's likely going to be very similar to DX10 where it adds a few nice features, but doesn't make much real world difference.
Well, has there been any word on when we'll be seeing dx11 nvidia cards?
Fermi is nVidia's upcoming new architecture, which will have DX11 support. It's still in the oven though, and there's no hard information more specific than next year.
nVidia would love to get the product out the door as quickly as possible, I'm sure, and I'd look for a release in early spring. The problem is that while they tell us things are coming along nicely, we don't have a lot of information right now to back that up, so they could be trying to convince people to wait on purchasing a fancy new ATI 58xx card (if you can find one, of course).