From the GG forum (http://www.garagegames.com/community/forums/viewthread/131946)
With the latest build of the Toolbox (1.1 Master branch), the Package Project button is no longer working to trigger the packaging code.
The Project Manager replaces the old Toolbox. It doesn't currently support packaging of the project, but it may in some form down the road. Right now the user will have to do it themselves.