Mesa 8.1 is a new development release.
Mesa 8.1 implements the OpenGL 3.0 API, but the version reported by glGetString(GL_VERSION) depends on the particular driver being used. Some drivers don't support all the features required in OpenGL 3.0.
tbd
Note: some of the new features are only available with certain drivers.
TBD -- This list is likely incomplete.
The legacy/static Makefile system (ex: 'make linux-dri') has been removed. The two supported build methods are now autoconf/automake and SCons.