SM3.0 support for the lucky bastids who have GeForce 6800 cards
Don't think there was any other major-ish elements included...else it would have ended up as DirectX 9.1...instead of a letter increment.
And hot on the heels of this new DX release is nVidia with their 61.77 Forceware drivers...not so sure if they're WHQL certified though as it's missing the customary "_whql" in its filename. But it adds support for DX9.0c
So....to answer your question in a more direct way...for peeps likle you and me who still runnin the last generation of cards (the ATI 9x00's & nVidia 5x00's)...not much
But I'm a sucker for software updates so I grabbed it anyways