Mathutils.Euler documentation for Blender 2.49 says that the input to Euler is in degrees. In Blender 2.49, it’s definitely in radians. That was scheduled to change in 2.5, but it apparently changed early.
The order of angles still has me puzzled. The documentation is vague on the arguments to init. The constructor seems to accept
Mathutils.Euler(roll, pitch, heading)
assuming that “heading” means rotation in the XY plane. There’s some question as to the order of the rotations. This needs to be documented. Figuring it out by trial and error is a pain.