We haven't seen a real upgrade, yet (I don't consider a drop-in CPU replacement as such), because of serious issues developing new drivers for the GMA X3100 graphics chipset (part of Santa Rosa). Almost no reusable code. The new unified shaders need everything to be written from scratch. Hardware utilisation is extremly difficult, due to Intels complex design of the chip. Lots of "don't call this function if that and this functions are being called concurrently". GMA 950 needed many workarounds, too, but the overall design was much more easy to program. Intel itself needed a whole year after product launch to ready its PC drivers and they aren't even complete, yet. No expertise at Intel for developing OS-X graphics drivers to assist Apple. Inhouse development was mainly focused around DirectX and Microsoft's powerful DDK's. There is no graphics DDK from Apple. They usually do all the work themselves. So Apple has just streamlined development and went Leopard only. The new Minis and Macbooks ship Leopard and there won't be drivers for anything before that. Else Apple would have had to maintain two lines of code for years without any (monetary) benefit. After all, the the flexible architecture should be a quite capable plattform for running OS-X. If Apple is able to utilize the unified shaders for its Core-Image architecture, we should see decents results (even for pro apps like Aperture).