Some good info right from Google!
If you sign up for their webmaster tools, you can designate how you want them to display your url in search results. The .htaccess was a need to do thing anyways...this is just the extra stuff if you want.
Canonicalization
To gain more control over how your URLs appear in search results, and to consolidate properties, such as link popularity, we recommend that you pick a canonical (preferred) URL as the preferred version of the page. You can indicate your preference to Google in a number of ways. We recommend them all, though none of them is required (if you don't indicate a canonical URL, we'll identify what we think is the best version)...