If you want to keep up on your friends’ Facebook activity but you hate keeping a tab open for Facebook, Facebook Desktop parks Facebook updates and a quick-reply function right in the system tray.

Facebook Desktop is an Adobe Air-based notifier that gives you simple access to updates as they occur and in replay mode (if you’ve stepped away from your desk for a moment). You can also post updates to your wall. To reply to the updates of your friends, double click the entry as it pops up; you’ll be directed to the actual post on Facebook as Facebook Desktop has no built-in reply tool.

Facebook Desktop is free and works wherever Adobe Air does.

Facebook Desktop [Adobe Air Marketplace via Digital Inspiration]