hey,
I havent heard of this myself, sounds interesting... it seems like a clever script if it can login to yahoo mail systems and access your account information such as the address book, I would of thought companies like Yahoo! would of restricted scripts from other sites to be able to do that, unless it is some sort of partnership.
can you give me some links to some profile sites that use such a script? I would really like to see it in action.
I wonder if yahoo and other online mail systems allow users to export their address book to some external file? if they do, you could obviously then get the user to upload that in their profile and have your script parse through it and pick out the addresses?