Add ability to add users by nickname/email from iPhone client.

Right now someone can tell me "Hey, I'm so and so on BrightKite" and I can't add them from my iPhone. I've been using SMS to do it to get around it, for now. I don't know if a search is really necessary, but just being able to "add by nickname" or "add by email address" should be sufficient. You could go really overboard with this and have it search the iPhone address book for registered email addresses, but that's probably something the privacy people will freak out about.. ;)