Re: Forums not indexed in Google!
There is a facility in the plugin to enter additional URLs that will be generated into the sitemap. This is a way to point google at “/forums/” for a bbPress installation that falls under a wordpress main site. If the sitemap is not valid then I expect it is unlikely that the sitemap will be crawled.
There are also other tools around for validating sitemaps but the google webmaster tools would be the one to trust.