It is hardware acceleration. It's just it's difficult to replace software mesa driver without breaking many things in the apt repo thingy, so the "wrapper" gl4es simply force to use alternate libGL binaries... But it hardware accelerate eveyrhing opengl basicaly (with the limit of what gl4es support of course, like opengl 2.1 and no more).Well, it's not really acceleration as I understand it. Unless software also has a software rendering method that this new GL path replaces, it could be considered so. But in most cases more recently, software only has the GL code path, which needs gl4es to interpret.
Edit: Well, Wally calls it acceleration on the previous page, so what do I know?