Bad update! Rated 3 out of 5 stars
Until last update all is working fine, now NOTHING WORKS! Right click doesn't show any options and there's no icon for the extension to add to the toolbar.
Version is 0.94 and Firefox 24.0.
I think I know the problem
I have rewritten the addon from scratch. There have been some change which will require you to configure the addon before you use it.
You will have to go to addon options (Firefox > Addons > Shorten URL > Options) and enable the select the services you want to use.
For bitly, you can now authorize it from Addons options as well using Oauth.