Apparently Alyssa Milano used her Twitter account to verify her Google+ account.
![Her unicode-fu is strong. Alyssa Milano tweet: this is my real Google+ account](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj0Ewmyz2YRGs6vnd4dkyN9PEZkkGOWR8SAZebiJaGyiBCsHypiaWfH0tb0nnZluZCTECL5j4GmsChONd-kULyuzgtnHCWe9v4l0AwLOjfag7LJBIwHdUC1X65ZNqL8zG52RY0mbas9zSzp/s640/AlyssaMilano.png)
XFN 1.1 defined a number of relationship attributes for links, one of which is rel="me"
rel="me" A link to yourself at a different URL. Exclusive of all other XFN values. Required symmetric. There is an implicit "me" relation from the contents of a directory to the directory itself.
Clearly, we need rel="me twitter" for situations like this.