RUTorrent is a Ruby library for the remote management of µTorrent clients via the Web UI API.

gem install rutorrent

require 'rutorrent'

s = RUTorrent::Server.new('127.0.0.1', 6881, 'username', 'password')
t = s.torrents[0]
puts t.name

Produces:

ubuntu-10.10-desktop-i386.iso

rdoc.info/github/cbguder/rutorrent/master/frames

As the version number implies, RUTorrent is undocumented and untested. Specifically, only read-only methods have been tested with µTorrent 2.2.1. Use it at your own risk.