Below a compilation of quotes from Google regarding Dynamic & Static URLs. See highlights in orange. Thanks Joe!
Info from Google.com Regarding Dynamic & Static URLs
Your pages are dynamically generated. We're able to index dynamically generated pages. However, because our web crawler could overwhelm and crash sites that serve dynamic content, we limit the number of dynamic pages we index. In addition, our crawlers may suspect that a URL with many dynamic parameters might be the same page as another URL with different parameters. For that reason, we recommend using fewer parameters if possible. Typically, URLs with 1-2 parameters are more easily crawlable than those with many parameters.
If you decide to use dynamic pages (i.e., the URL contains a "?" character), be aware that not every search engine spider crawls dynamic pages as well as static pages. It helps to keep the parameters short and the number of them few.
Consider creating static copies of dynamic pages. Although the Google index includes dynamic pages, they comprise a small portion of our index. If you suspect that your dynamically generated pages (such as URLs containing question marks) are causing problems for our crawler, you might create static copies of these pages. If you do, don't forget to add the dynamic pages to your robots.txt file to prevent us from treating them as duplicates.
http://www.google.com/support/bin/answer.py?answer=745 (Duplicate content)
Don't create multiple copies of a page under different URLs. Many sites offer text-only or printer-friendly versions of pages that contain the same content as the corresponding graphic-rich pages. In order to ensure that your preferred page is included in our search results, you'll need to block duplicates from our spiders using a robots.txt file. For information about using a robots.txt file, please visit http://www.google.com/remove.html