Ton has published the development roadmap for Blender 2.44 and 2.50. 2.44 will be worked on during April. It will be a release with mainly bugfixes and minor improvements. This will be the last release before 2.50 which will consist of the long expected UI overhaul and other feature upgrades. The tentative releasedate for 2.50 is october/november 2007. Check out the report on Blender.org.