Thanks for replying to this thread.
I've already tried setting up my Bit.ly account at Administration -> Settings - > Twitter, but somehow it doesn't work as expected. When I visit this page it says "The resource cannot be found." Then I click OK and the attached image shows what options are (or aren't) there...
So, as you will see, I don't (or it seems I don't) have the option to add my Bit.ly account settings.
I tried adding my Bit.ly account by going to Administration -> Advanced -> System -> UrlShortenerConfigDescriptions, but that didn't help either.
Hope you can help me out here. Thanks again for you reply.