Yes, Twitter retired their API v1 yesterday. So Twitter widget no longer works.
The big problem is that their new API requires users to set up an API app and get a key. The widget needs to then authenticate against the API to get tweets. We are looking at it right now, but seriously considering retiring the widget..
Any new widget will require you to create a Twitter app and get an API key.
Sorry!! Typed too soon. If you go to the homepage of the twitter handle that you are managing–click on the gear icon and choose settings.
From there click Widgets, and Create New
There are simple directions to create code for a user timeline, Favorites, List, and for a search term. Fill out the form and it produces code for you to paste into a ThemeLoom text widget, and taa-daa! All done, no finicky Twitter API development needed.