It would be great if exporters for applications like Blender could export directly to the WMB format.

Could you release the specifications for WMB or do an IO-library for it (but please with a C-API so that other languages than C++ like Python can easily access it)?

Blender 2.5 will have a much more customizable GUI so it will be possible to turn Blender into an easy to use level editor which is much more powerful than WED.