So an idea that has been floating around for some time is that you can verify that a link a person puts in their profile belongs to them, by checking if the linked site links back to the profile (with a special attribute that signifies intention), and that it can be used to, indirectly, verify that a profile is "real"
@Gargron You could just check out App.net’s code to see how they did it. Theirs was DNS based.
@JonathanGerlach DNS doesn't work as well because not everyone knows how to edit DNS records. It's easy to put a rel="me" link in your tumblr bio, or drop in on your sharing hosting site, but it might not even be possible for you to edit your DNS records.