Google: You need identity
plus.google.com
plus.google.com
> The TL;DR version for implementing rel=”author” is that it requires three specific links.
>> A link from your blog post or article to your author page using rel=”author”
>> A link from your author page to your Google profile page using rel=”me”
>> A link from your Google profile page to your author page using rel=”me”
Even if not everyone eventually obtained their own domain name, the idea of using some URI as a (self-chosen) identifier seems to me attractively powerful - as long as one is able to re-select at later time).