The things about chatrooms, is they're very controversial. You have them and members will be happy, and only post in the chatroom, this will kill the forums, and future development/growth of the forums. You don't have them, and members want them, but it allows everyone to post actively on the forums. On top of all that, chatrooms also take up a lot of bandwidth, and slows down the forum a lot. With having a chatroom load times could spike, and double. It's something I'd have to sit down, and really think about, as well as go over it with the fellow (Currently small) staff about this.
Sorry for the long post, I like to explain the reasoning behind why I don't want to add it, vs. saying "We're not going to add it". This way you understand the thought process behind decisions, etc.