I've been working with sproutcore in my spare time for almost 6 months now and along the path I came up with some nice (I think) components.
This one is a tiny unintrusive mixin that can be applied to panette panes and adds a close button on the top right corner. I have tried to make it work on panel panes too, but without success so far. That is probably because panel panes, being modal, grab all events before the events reach the mixin.
Fetch from my github account:
P.S.: I also have a functional OpenLayers view, but it requires some refactoring before I can make it public.