SEO Sitemap is an add-on to OSC that enables search engines to see
the catalog pages properly. This tool creates 2 important sitemaps:
One that contains all of your categories, the other contains all your products.
All the links in the sitemap pages terminate with '.html' instead of '.php'.
Normal users will never see these pages. Instead, they are automatically transported to
your site's true homepage via a java redirect.
Search engine robots will ignore the java redirect and will see these pages. These sitemaps
should allow all the major search engines to see and include in their index all your categories and your products.
I would highly recommend that the excellent "Meta Tag Controller" contribution, which allows you to customize both META keywords and descriptions at the individual product level, be istalled on any site where this SEO-sitemap is installed.