As an Obama supporter, I have seen this button availible to add to your own website or whatever:
Here's what bugs me about it: you don't join a profile. You can join myspace, you can join the Obama campaign, you can join my.barackobama.com. When you add someone else's myspace profile to your friends list, the appropriate verb is "add as friend." It would barely make sense if I decided I needed more myspace friends and begged everyone who reads this blog to "join my myspace profile!" You could even say "join my friends list." I think the button should say "friend the official myspace profile" but some quarters criticize my use of "friend" as a verb. However, I really do think that's how people talk about myspace actions. Perhaps as a happy medium, they could say, "join the barack obama campaign on myspace."
So, basically, I think this wording makes the Obama campaign seem un-savvy. Perhaps it's not the savvy audience they're reaching out to, but seeing as it has to do with myspace, I don't find that a satisfactory conclusion.