So it’s not really a metric of his popularity, so much as of how many people he could add as friends. It’s like saying someone who has 50,000 numbers in their cell phone, but receives far fewer calls than other people daily, is the most popular person alive.

His followers — which is how many people list HIM as a friend, and would seem a more accurate popularity metric — put him at the 9th most popular on the site.

Still no small accomplishment, but an unquestionable misrepresentation by Slate, probably due to a writer who didn’t take the time to fully learn the vernacular of the service in question.

For the record, you can see detailed stats on Twitter popularity here, amongst other places:
http://twitterholic.com/