Short update: in a conference call Tim Cook explicitely said that Apple won't build a netbook/mini laptop with this generation of processors (i.e. Intel Atom N270 and VIA Nano).
According to Apple, current processors are too slow, not sufficient for a good customer experience.
Let's see whether a dual core Atom or next generation of Intel Atom (Pineview, with integrated graphics and memory controller) will have sufficient performance, according to Apple.
To be noted that what Tim Cook said could be an answer to what an Intel executive said a few months ago (iPhone internet browsing is slow because of the ARM processor), furthermore there are rumors of Apple being developing an own processor, to be used in Apple Netbooks. It means that Apple may enter the market with an own processor and is already starting the marketing campain saying that current processors are too slow...