I stumbled upon this just now and I thought it would be good to share for anyone who is interested.
There now is a plugin for pidgin (who knows, maybe it will become official one day, myspaceIM did) that allows you to login and chat with people who are currently signed into facebook. You can also see their profile picture and their status as well.
To install and use this plugin, if your using Ubuntu, simply head over to this page:
and download and install the deb.
If your using windows, download the .exe here:
Once you have installed the plugin, simply just add a new facebook account, and for your login, put your email and your password. There are some settings in the ‘advanced’ tab that you can configure when your setting up your facebook account in pidgin, such as having your pidgin status be your facebook status, whether you want new facebook notifications to show up as emails in pidign, etc etc. Configure them to your liking, and chat away!