Transmission 2.0 (Bittorrent client for Linux and MacOS X) has just been released, featuring "Local Peer Discovery" for finding peers on your local network, optimize download requests for the bandwidth available, faster local data verification and startup, smarter heuristics when deciding the order to connect to peers, use IEC standard units (KiB, MiB, GiB) instead of (KB, MB, GB) and many other new features and improvements.
There are several improvements to the GTK+ interface too: the netbook owners will be glad to know that the compact view takes up less space and the 'Properties' window fits on low resolution screens. There's also a new filterbar to filter by tracker, favicon support for the Propreties dialog Tracker tab and many more.
A full list of changes can be found @ Transmission website.
Install Transmission 2.0 In Ubuntu
To install Transmission 2.0 stable in Ubuntu Karmic and Lucid (for now, they might upload builds for older Ubuntu versions too), paste this in a terminal:
sudo add-apt-repository ppa:transmissionbt/ppa && sudo apt-get update
sudo apt-get install transmission
For other Linux distributions and MacOS X, see the Transmission download page.