While Google may not have intended their new Goo.gl short URL service to be used anywhere other than the Google Toolbar, I doubt they're too upset about developers figuring out how to tap into it.

Three extensions have already popped up in the Google Chrome Extensions Gallery which offer Goo.gl truncation in your browser. ChromeMUSE, which I've been using for a little over a week, pushed an update last night which added Goo.gl support.