at the moment if anyone tries to PM you via the drop down options under your name you get this message
"Red Panda has chosen not to receive private messages or may not be allowed to receive private messages. Therefore you may not send your message to him/her."
I have no idea how you undo that (moderators help?) but I'm sure you'd get lots of interesting messages should PM's be made available to fellow chatters?
If you click on Control Panel at the top right of the screen, then look for 'Edit Options' in the lefthand side and click that, you'll see the Private Messaging setting there.