It will do it automatically... Any page that is in Google will be included (since it uses Google as the backend). Google does spider PHP pages, so as soon as Google knows about them, the search engine script will have them in the results. - Shawn
so this will only work if Google has indexed your pages... it doesn't just seach that directory as a query is made?
Correct... it uses Google as the backend database (which is why you don't need a database or anything on the server itself). - Shawn