^ It is. I've spoken to somebody who had played BF3 Alpha with a 6870. While he did tell me that the game was more than playable with that card, he advised me to purchase either a 560 Ti or a 6950.
My first preference was a 6870 actually. But then again, I chose that card because I had plans of crossfiring it in the future as dual 6870s > dual 560 Ti's. But now that I've decided on getting a 56O Ti, I may never add another card if this one card is sufficient to play BF3 at 60fps high. Judging by the recommended specs released by the company, this card should achieve that.
p.s : BF3 is better optimized on nVidia. I'm basing this on the recommended specs released by the company.