The newest version pending approval works with 4.7.3. It brings back the birthday widget AND even shows multiple days. (It does not use the calendar system to get data so it can work in the new version.) Check out the screenshots above. 🙂
There is a sidebar and a wider version of the widget. (This app was originally custom developed for me, so it also has some filtering requirements I had.)
Rumor has it that Adrian is also working on a birthday full page display (that may possibly just happen to coincidentally look like a calendar as well).