I'm currently involved in implementing ubbthreads as a forum for a newssite, and we also got a lot of usability issues going on. so far the testing has only been with internal staff, but this has already brought some helpful hints.
newbie users are confused with many things - icons, graemlins, ubb-code, colors, last post...
most striking: newbies often do not know if they are logged in or not.
the biggest problem with ubb-code: users mark some text and then hit the code-button, e.g. bold - and the text disappears (they probably hit enter without filling in the javascript-popup)
one could say, they will learn about that - but it would be easier if they were not forced to learn ("don't make me think" as this is called)
