That will definitely be nice for those products with an integrated graphics processor - MB and MBA. Thing is, the current X3100 is being held back by lack of mature drivers for it. The previous generation (x1600? I forget) outperforms the x3100 in some benchmarks because the drivers are much superior. I have not seen any new benchmarks after the "graphics update" with 10.5.2, anyone seen some? The question becomes not how is the hardware, but how is the software??
Oh - and I love on that chart the ~2x performance with a scale of 0-2 on 3dMark06 lol...