Google has announced that you can tell them what URL is correct. This is very helpful for enforcing URL’s. The new feature is called
Google says they treat it as a “hint that we honor strongly” I still believe that you should enforce url’s yourself programaticly using 301 redirects. One of the reasons for having nice short URL’s that contain Keywords in them is to make it easier for people to link to you. It is also to make it easier to email your link and post links in chats or forums. You don’t want people using www.tinyurl.com for your links because you are now advertising tiny url and not your site.