I doubt anyone ports Limewire or Bearshare etc. to the iPhone because they are way to commonly used illegally for copyright infringement of music/movies etc.
Also I would advise you didn't use Bearshare for a few reasons. It has alot of security issues.
http://www.auditmypc.com/process/bearshare.asp
There are also reports of people connecting to leechers (you, the downloader) by using their IP address and more obtained by the connection and transfer process, and they were browsing files and information on unsuspecting downloader's computers. Just something you might want to keep in mind.