Mark Shuttleworth, the founder and leader of Ubuntu, recently announced the next version of Ubuntu - Karmic Koala (v 9.10) will improve the Ubuntu experience on netbooks.
Mark Shuttleworth mentioned he aimed to get boot times down to 25 seconds on netbooks, which is quite impressive because Ubuntu isn't a light-weight Linux distro, because of its many features/applications.
The Ubuntu Netbook Edition will make more improvements for small screens & tuned to work even better on screens that are vertically challenged. Also the Ubuntu Netbook Edition will be updated to include all the latest technology from Moblin & improved compatibility for all netbooks.
The former Ubuntu Netbook Remix release was quite popular last year (see the screenshot) & got some good reviews, so it became the primary OS for a lot of Netbooks.
Look here for the official Ubuntu 9.10: Karmic Koala anouncement.