Erick Perez Castellanos announced in his blog yesterday that Gnome Calendar is moving forward!
There is still a lot of work to be done, but the development of various aspects has been re-started. The most important is the implementation of the event-view that is missing functionality, but the widgets part is almost done.
Below you can see some screenshots that show the month-view and the even-view. There is still a lot to be done, like the addition of more elements and the use of some symbolic icons etc, but you can get the idea from these “skeletal” designs.