I'm currently looking at Google sitemaps, so it's rather spooky that this topic has come up!
I agree that the use of mod_rewrite is an excellent tip for anyone with a website that uses dynamically generated URL's - We only use CMS's and Ecommerce systems that make the use of mod_rewrite, just because of this very reason...
Back to the first point and Google sitemaps, has anyone actually seen an increase in hits after installing sitemaps?
It seems to me that Google has given up trying to spider dynamic website's - using sitemaps to get the webmaster to do the hard work and then the lazy spiders just have to follow the maps
