The 7750 & 7770 are out but not good on price/performance compared to the 6850 & 6870. The only unreleased (shortish term) product that may compete price/performance with the 6770 will be Nvidia.
i would get a 7750. its a little slower than the 6770 right now but it has very early drivers. it should be 5-10% faster in a couple months. plus it uses a good bit less power. and its always good to have a low power bill.