Google's Vanessa Fox of the Webmaster Central team just announced a slight change in the webmaster guidelines.
The old guidelines stated:
"Don't use "&id=" as a parameter in your URLs, as we don't include these pages in our index."
Vanessa now notes:
"However, we've recently removed that technical guideline, and now index URLs that contain that parameter. So if your site uses a dynamic structure that generates it, don't worry about rewriting it -- we'll accept it just fine as is. "
If you are a search marketing professional dealing with natural search optimization, be sure to check out the entire post - she points out a bit more. If you didn't know it, the search engines tend to have issues with dynamic URLs that contain numerous parameters in their URL strings.