The next version, 9.04 Jaunty Jackalope, is almost at feature-freeze time and is scheduled to launch in April, in accordance with Ubuntu's strict 6-month release calendar. Karmic Koala should follow in October, so it's a while off, but it's cool to see what's coming up in the future.
There isn't much info on Karmic Koala yet, just some broad outlines of the direction the team plans to take Ubuntu. It'll be optimized for netbooks, since the advent of the mini-lappie has resulted in a lot more Linux users, with profiles allowing for their shorter screens. Karmic Koala should also have a new strategy for taking advantage of cloud computing; there aren't any specifics, but it seems clear there'll be some sort of significant push.
For the aesthetics, 9.10 promises a new look, with a flashy startup screen, quicker boot times, and the end of the iconic brown theme. More details should be coming at the Ubuntu Developer Summit in late May. [Ubuntu]