If we're going to conform to one, Intel's definition of a netbook is probably the closest to sensible going and if HKEPC is right it's been extended to make even more sense. Fear not folks, I won't be changing my Intel's definition of a netbook classification any time soon as a result.
Supposedly Intel is relaxing the limits on what screens can be uses in conjunction with Atom. The previously 10.xin or smaller size ceiling will remain but resolutions above 1,024 x 600 are now allowed. In other words: an N-series netbook-orientated Atom CPU can now be paired with a 1,366 x 768 pixel display.
Such claims seem backed up by the likes of the Sony W Series and HP Mini 110, which both offer the pairing of a 1,366 x 768 pixel screen with an Atom CPU. Given sales of netbooks seem to be slowing, it's hardly surprising that the remit of what can be classed as one is expanding - by differing degrees depending on which classification you prefer - to fit higher-specced systems. Whether that suggests netbook customers now are more discerning or just pickier is a matter of debate, however.
How long now until a 10.xin, 1,366 x 768 pixel screen, a dual-core Atom CPU and 20 hours of battery life become standard netbook specs? I might even be able to give up my not a netbook rant, soon!
HKEPC (Google translated).