Issue With rel=”me nofollow”

I’m going to make the effort (again) to use twitter so I’m tweaking my account. I’ve just read a post by Dave Naylor about plonking a URL into your twitter bio to gain a backlink – good tip! The standard web link in your profile is nofollowed but if like me you use the SEO for Firefox add-on, that no-followed link won’t appear in red to indicate such. I’m presuming this is because twitter uses the html code rel=”me nofollow”. I don’t know what the me attribute does though – maybe it’s specific to twitter?