Intel started shipping the new Atom N280 together with the GN40 chipset. Both N280 and GN40 aren't mentioned at all in Intel website.
Intel deleted the the confidential document with first official information on CPU clock 1,66GHz (just 0,06 GHz more) and bus of 533MHz while news sites worldwide talk about 667MHz FSB.
In any case, we'll see very soon the first Atom N280 netbooks. Asus and others already announced the first models.
GN40 vs 945GSE: voice say that the (compared to the 945GSE) the FN will have much better 3D performance and will be able to play high video (blue ray). On the other hand, according to unofficial information, the Atom N280+GN40 should be slightly less power efficient.
GN40 vs Nvidia Ion: I doubth that the GN40 will outperform the Ion in 3D performance, Intel doesn't have a big 3D tradition however who knows...
In any case you know what I mean about 3D performance and benchmarks for netbooks: I'm sure that 3D games are not of interest for the vast majority of netbook users! Who really cares about 3D benchmarks for netbooks? If you want to play 3D games you won't be happy with a netbook, the display is far too small and the processor isn't that powerful...
Other posts on Intel Atom