So anything <=R500 is not 100% OpenGL 2 compliant hardware?
I had to read that over a few times cause I wasn't sure I was understand it right. I guess nobody would have really known without free drivers. I guess that's another reason for open source stuff.
Actually, it was pretty known that R300-R500 were not GL2.0-compliant (*), but the missing features are simply not *that* important or useful. NPOT textures carry a performance penalty and are difficult to mipmap correctly, so they aren't used for regular texturing. Their main uses are viewport-sized FBOs and (more uncommonly) 2d graphics, which do not need mipmaps at all - no big loss.
Edit: (*) it was pretty well known among game- and 3d-developers, at least.