This is similar to my own idea for how to authenticate a Twitter verification esque setup; having the user upload auto generated files to their server and the site check for those, like how Google verifies accounts in Webmaster Tools.
The issue however is that I suspect verification should also have the purpose of verifying that the individual/group doesn't just own a third party domain/resource, but that they're the owners of the version people associate with that name. All these systems make it very easy to just register say 'Microsofte' and end up with a verified account called 'Microsoft' or what not. That's going to allow for a lot of easy impersonation.
The issue however is that I suspect verification should also have the purpose of verifying that the individual/group doesn't just own a third party domain/resource, but that they're the owners of the version people associate with that name. All these systems make it very easy to just register say 'Microsofte' and end up with a verified account called 'Microsoft' or what not. That's going to allow for a lot of easy impersonation.