Allow users to search for other users using username/email in the iPhone app

I would like a way to search for friends easier on the iPhone app. Today I had a friend tell me they were on brightkite, so I whipped out my iPhone and went to the friends section and hit add. I assumed I could just search for him using his username. I found a Discover friends via address book, and two ways to invite friends. Well I didn't want to invite him, he was already on brightkite. I didn't have him in my address book either. I knew his brightkite username though cause he just told it to me. So instead, I had to exit the brightkite app, go add him to my contacts, then go back into brightkite and then do the Discover. It would be nice if you could just search using username, name, email, or phone number.