While one half of the developers were busy with the 2.5 project, the other half happily continued working on directly usable and useful features in Blender. Especially advances in the Game Engine justifies having a well tested, bug fixed and stable 2.49b release.
Check this impressive long list of features!
blender.org team, May/June/September 2009
List of reported problems in 2.49, an update release has been done now.