The hsf is different, there is a temp sensor, it has the overdrive feature (not yet supported, even though the cat 3.9 are out), and it comes with hl2.
The 100 mhz increase makes a difference (not a huge one, but a noticeable one). If you add HL2 to that, I think it's worth the price, if the prices are anything like at my local shop.
Of course HL2 won't be out for a while, so it may seem like a ripoff if you consider that.
EDIT: Basically, the two best features of the card are unusable as we speak: HL2 and overdrive.