I tried friggin' with mod_rewrite and came up with this, its probably pretty cruddy, so, someone can fix it up if they'd like:
02/12/01 :: a couple minor fixes/additions, take it for what its worth...[note, you can add "[R]" in the fourth tab'ed column so that it'll redirect to the long URL instead of showing the short URL]
chuck that into a .htaccess file in your /ubb/ dir and your urls go from:
http://www.whatever.com/cgi-bin/ultimatebb.cgi?ubb=get_topic&f=6&t=000086&p=2 to
http://www.whatever.com/ubb/6/000086/2 39 chars shorter... (in this case)
[ February 12, 2001: Message edited by: MC_Mouse ]