"About page" and homepage are now two different genres. Marina and Mirko, you are right.
Marina: I consider "about page" an kind of emerging genre: it is not fully recognised and acknowledge by people. On the contraty the "home page" has a very clear identity: it is the entry page of a web site. Navigationally, you go can go back to the home page anytime, by clicking to the little house, or to the word "home". I think it is really one of the most idenfiable genres to humans dealing with the web. I think it is highly plausible that home pages belonging to different domains (organizational, commercial, personal) can be characterized slightly different thus becoming subgenres