>Is the forum actually getting crawled?
Yep - even on page x in the serps for targetted keywords - eg. "widget forum".
>No session ids or logins getting in the way?
No session id, or login... unless you login.
Yep - very friendly, short and mod_rewrited.
eg. /Forum/1/ /Threads/1.html
>The only filter you've hit is the 'google hasn't updated its toolbar PR' filter
Should have thought of that myself - anyone know the last update was?
I'm expecting a PR5 and better ranking than I see currently - luckily I've been at this game a long time and learnt the golden rule - "Be patient".