When someone adds your User ID to their YouTube address book (easily done with the Navigate YouTube iPhone app), you will receive an email request to become a friend of the requestor. If you accept the request, then you are promoted from an ordinary contact in their address book to a friend.
Similarly, you can easily use Navigate YouTube to request that a contact be converted to YouTube friend status. You can then look at their activity and better share your interest in YouTube video.
Navigate YouTube makes it easy to use the iPhone/iPod Touch to review the YouTube activity of one’s friends. In the example screen shot below, Pam is a friend. It is easy to review some of her recent YouTube activity. This is a great way to find interesting new video.
This feature, along with other interesting YouTube access features, is now part of the new version 1.3 update. The app makes it easy to be a YouTube expert-user.
There is more info at the iTunes App Store or at the user instructions webpage.