I read that if the sites files are on two domains, it probably wouldn't work...but I'm assuming different directories would be okay? (I.E.
http://www.sarcasticgamer.com/wp and
http://www.sarcasticgamer.com/forums)
Also, how does this affect the site's performance? Here lately, we've been getting the 'Digg effect' (craploads of traffic within a short amount of time) about once a week or so...it'd suck to start using this and then be offline throughout the Digg wave.