wicd is a simple yet powerful wireless connection manager that boasts built-in WPA support. It isn't supported by Canonical yet, so you need to add their repository manually, update you package lists, install it, and configure it for easy usage. After following these instructions, you can run the wicd-tray program when your desktop manager starts in order to place an icon in your system tray, or you can start the graphical interface itself using the wicd program (actually, they're symbolic links to python programs). Simply enter these commands into a terminal:

echo "deb http://wicd.longren.org feisty extras" | sudo tee /etc/apt/sources.list.d/wicd.list sudo apt-get update sudo apt-get install wicd sudo ln -s /opt/wicd/gui.py /usr/local/bin/wicd sudo wget -O /usr/local/bin/wicd-tray http://blakecmartin.googlepages.com/wicd-tray sudo chmod 755 /usr/local/bin/wicd-tray

And you're up-and-running with wicd!

* note: The wicd package conflicts with other wireless connection managers, such as wifi-radar. Installing it will require you to remove their respective packages.