While in the applications we tested there hasn't been any notable gains with the HD 3870 X2 actually taking a hit in a few cases, the new drivers generally seem to be increasing performance in the promised sections for people.
What's really interesting about this driver is if you take the time to read the performance improvements, they all revolve around DX10 improvements. It will be interesting to see if this is something we begin to see more of over the coming months; Vista has really picked up momentum in the gamers market with most people jumping onboard.
Considering how hard at work AMD has been on the new HD 4800 series, it's surprising to see any real gains from this month's driver, but they've managed to do it. No doubt over the coming months AMDs focus will begin to move to the HD 4800 series of cards in a continuing effort to compete against NVIDIA.