Im replting by phone now, so i cant give links... but there are some seo sites and even a script that will allow you to enter the address of your sitemap and will ping all the search engines to tell them your sitemap has been updated. very useful i think. if you remove a category and google tries to crawl it based on information found in a sitenap created before the cat was removed, then you will get errors. i like to notify them instead of waiting for them to find out themselves.
