If I recall correctly, the free version of Sketchup can export to the Collada format (.dae), which is not the best interchange format, but it can be read by Blender and other 3d programs. The only real problem I had when I was working in a Sketchup -> Maya pipeline was that upon export to Collada, the mesh was triangulated, so I had to retopologize the models before I could continue working on them.

Sketchup Pro can export to several other interchange formats like FBX and OBJ, and it can even send straight to 3DS Max.

So no, I wouldn't say you're necessarily wasting your time in Sketchup, although it depends on where you eventually want to be using your material. SU is common in cartographic-related circles, since it interfaces directly with Google Earth. It's also got a decent user base in architecture. You won't find it much in the film or video game segments, though.