You can read about Google Parameters in detail on the link below: http://support.google.com/webmasters/bin/answer.py?hl=en&answer=1235687
The URL parameter are some thing like: http://www.example.com/products/women?category=dresses&color=green In this example, you have a parameter of category and colors. Google always emphasis on user friendly url and parameter. If you place your url outside you website then the user should know form the url, that what it about. Also Google emphasis that use URL parameters tool to tell google the purpose of the parameters, you use on your site and how Google handle URLs that contain those parameters.
I think it is very important to stuff your keywords in your url, the idea is to deliver enhanced usability to help users remember and share your URLs more easily.
I think URL plays an important role in SEO, we should always optimize the format for SEO friendly url. For instance "www.yoursitename.com/post title" is been considered much seo friendly as it claims what is article all about. Neil writer @ Gizpad