I make a 3D shape, like a sphere or a cube, then I put a texture on it and modify it's tex coords in the texcoord editor. (It looks good in the 3d windows when I have alt-z enabled).
However, I've also written a script that exports that model into my own ascii 3d format. And it won't export the uv coords, it only put 0.000000 in that place.. here is the line in my Python script:
for vert in m.verts:
self.m_f.write("%f %f %f %f %f\n" % (vert.co[0], vert.co[1], vert.co[2],vert.uvco[0],vert.uvco[1]))
Everything else in the resulting file seems fine (like the vertexcoords)..