Some phpbb sites are using Google to search their forums (see, for example, [url=http]phpbb.com[/url] and [url=http]IM.nl[/url]) and I wondered if anyone else was using Google and how you'd modded it into your site.
I read on phpbb.com that it takes a lot of pressure off your db if you use Google so it may be in our interest, too. Also, I've found the phpbb search feature to be not too accurate <img>