A few weeks ago, we mentioned uTorrent's new, native Mac client moving to beta, sporting a new UI and all torrent-downloading features you could want from something lightweight. The project is still in beta, but officially got the 1.0 label this weekend, so it looks like we're getting closer and closer to an official release.
There are a few new bug fixes, but nothing super new in this release. If you were waiting for a more stable build, though, this would be a great place to start. After testing it for awhile, it doesn't seem quite as lightweight as Transmission on my machine, but if you check it out, be sure to let us know your experience in the comments.