Wiki
The interface is kind of a bitch. You have to click "REPLY" under the exact post you're trying to reply to, otherwise the default is it will put your reponse in under the original starting post. On long, complicated threads it gets to be a real zoo.
The plus on this interface is that if you hit the first post in a thread, all the posts show up and you can scroll down to read at leisure instead of having to open them one at a time.