A few interesting points.

1. Google can, in fact read dynamic URLs, and if you believe this post wholly, probably better than you may have thought previously.

2. Google says limiting to 3 parameters is unneccesary and maybe even harmful to indexing attempts. Personally, I think there may still be times this can be smart to do, but it seems like you probably have to think about it a bit more to get it right in some cases…

Google wants you to let the ENGINE decide what is important and what isn’t. Their actual recommendation is to NOT rewrite the URL. That’s great, so long as the engine knows whats on your mind for importance on a page… I’m still willing to bet a smart SEO is better off figuring this out himself and holding the engine’s hand still for a while longer…

Google did provide a few guidelines to think about:

1. It’s quite hard to correctly create and maintain rewrites that change dynamic URLs to static-looking URLs.
2. It’s much safer to serve us the original dynamic URL and let us handle the problem of detecting and avoiding problematic parameters.
3. If you want to rewrite your URL, please remove unnecessary parameters while maintaining a dynamic-looking URL.
4. If you want to serve a static URL instead of a dynamic URL you should create a static equivalent of your content.