The only proper new "feature" is support for PowerXpress GPU switching when using an AMD IGP and an AMD discrete graphics card. This is just dealing with switching between integrated and discrete graphics when both of them are being controlled by the Catalyst / fglrx driver. This unfortunately is no good if you're hoping to switch between Catalyst and the open-source Radeon KMS driver or with discrete/integrated graphics from other vendors.
There is a fairly nice number of bug-fixes in Catalyst 11.7. Among the fixes are for CrossOver, output lag, corruption when applying RandR 1.3 transformations, various PowerXpress system fixes, and mouse pointer positioning problems on rotated screens.