Yeah, the search function only seems to pull posts that have appeared since the site's relaunch. (Which, for my needs, put me in a panic for a bit.)
But thanks to (my new best friend) Google [Bot], there's a workaround using Google's Advanced Search:
http://www.google.com/advanced_search?hl=enType in your keyword(s), and in the "Search within a site or domain:" field, type in "www.stewartcopeland.net/forum" .
(Alternatively, you can go to the regular Google page, type in your keyword, and then add "site:www.stewartcopeland.net/forum" to the field, and it will function the same.)
Dramatic highlights & a unique musical cosmos. Guaranteed.