Here's a snapshot of the netbook market in March 2009: 19 netbooks for $350 or less.
http://www.liliputing.com/2009/03/19-netbooks-for-350-or-less.html
These are base configurations in many cases, so it's pretty easy to add memory or a disc upgrade that will bring the total to more than $350. A similar list in October 2008 by the same author set the ceiling at $399, so some progress has been made.
In six months, I expect prices to fall to less than $250 to clear out today's models. The computer manufacturers will need to make some space for new models running the latest low power CPUs and improved graphics processors (faster, longer battery life, better able to handle HD video). The new machines will be noticeably superior to today's netbooks.
Looking into the crystal ball, I see a showdown coming between Windows 7, Google's Android and Palm's WebOS on small portable devices. (I don't see unix/linux distros gaining much more market share than they have now.) Netbooks are not the place to run Word and Excel, so Windows 7's major advantage is reduced. Android and WebOS will be faster, quicker to start up, better linked to telephony features, and better linked to the Web than Windows 7. Oh, and a lot cheaper than Windows 7. If people have to pay more than a $50 premium to run Windows 7, then I think Android and WebOS have a good shot.
Chip Haven