I was watching Gamespots On the spot. And they sort off confirmed it.
This is supposed to make a big difference in computing power.
DirectX 10 Makes graphics and calculations consume less power than it normally would. Normally the calculation would strain the CPU but with DirX 10 the Gfx card does it all. They seem excited about it beeing used on Wii (atleas thats how I interpreted it)
You can see On the spot here. And the DirctX part is 10min in.
http://www.gamespot.com/pages/features/onthespot/index.php