I have a few sites in my Google sitemaps control panel. The second I log into "Webmaster Tools", Googlebot visits all my sites (and sticks around sometimes). Anybody know why this is exactly? Not that that's a bad thing.
Maybe to tell you if there is any problem with your site and to check if you've put a sitemap there..
I think that the google indexing on the siteson a specific period of times. That will depents upon the time specified on the sitemaps.