With Apollo out of the bag we are now seeing other tools performing similar functionality.
The one that has caught my eye today is Slingshot by Joyent. As a Ruby on Rails developer this realy has fired my creative mind. From what i have read on the Joyent blog, Slingshot will allow you to build Rails applications for the desktop and run the offline.
More information:
I will publish more information about this new technology when I have been able to create a test application.