In the old days -– say six months ago -– netbooks were easy to describe in a few short words. Cheap (less than $400), small (10-inch screen or less) and light (less than 3 pounds). Alas, things are not quite so simple anymore.

The netbook category’s parameters were already expanding as the market flooded with new offerings. Screen sizes crept up, as did retail prices.

And then along comes Sony to really confuse things with its Vaio P Series Lifestyle PC, which it unveiled at the Consumer Electronics Show. It’s plenty small (8-inch screen) and light (1.4 pounds). But note that decidedly un-netbook-like price tag: $900.

Of course, the company itself is not calling it a netbook either, although plenty of others are. And the impressive array of high-performance bells and whistles Sony packed into the little laptop might well justify the hefty price tag, and succeed in separating it from its similarly small, yet more stripped-down and lower-market peers.

So call it what you want, netbook or mini notebook or something else entirely. The Vaio P is simply the latest evidence that ultra-portable computers, though they may be small, are succeeding in redefining the PC world.