Symptom: When you try to create a new chatroom from the Lync 2010/2013 client, you are redirected to a webpage that shows the following error:

User is not sip-enabled.

Solution: Turns out this is an issue with cross-compatibility between Single-sign on and 3rd party browsers.  Make sure you are using Internet Explorer and you should be able to login and manage your persistent chatroooms.