These aren’t only mockups, are just experiments but some things look quite right, like the refined Calendar menu in the first mockup.
So what Jakub Steiner (Jimmac) did here, was to add the new notification system (coming in GNOME 3.14) to Shell Clock!
That obviously works in addition with the bottom screen-edge notifications. The designs are experimental and quite fresh (10 mins ago). You can find them at Github!