Update - Shmoocon already had a list:

http://lists.shmoo.com/mailman/listinfo/shmoocon-roommates

Go with what your readers want right? Well I have recently been getting a lot of hits on finding room sharing at ShmooCon. I have done this before at cons and I have met some very interesting people. So I created the google group ShmooCon RoomShare. Post that you are looking, post that you have space. It’s all voluntary and you can sign up for email alerts so that you don’t have to check it all the time.

Plus, you don’t have to share for free, if you are looking to split a room, the conversation can start there.