The extension adds a button to your urlbar so you can shorten or expand the urls in the urlbar
The extension automatically copies the shortened or expanded url to your clipboard, so you can paste it on Facebook, Twitter, your blog, etc.
You can also shorten or expand links in web pages through the context menu. Also works with urls in plain text format. Just select the entire address text and right click on it.
This extension uses the new Google Shortening API released just days ago.