Google on static vs dynamic URLs

Google have just posted to their Webmaster Central blog about the use of URL rewriting to convert dynamic URLs to static ones, incorporating querystring parameters what the user and browser see as a folder structure, eg domain.com/products/books/193872. They make some excellent points about the difficulty they face in knowing which part of such a URL is actually dynamic, and which isn’t - a very interesting read

For more info on URL design, these ALA articles are brilliant:
Slash Forward
How to succeed with URLs