MakerBot Print is our newest print-prepration software, which supports native CAD files and STL assemblies,
allows you to interact with all your printers via the Cloud, and many other exciting new features.
Another printer smartley moves its Z-Motors to the bottom of the bot. Well played :) I am also a fan of driving the Z axis with a single motor, using a belt system to turn both rods at once.
The SeeMeCNC H-1 printer does this, and it seems to work like gang busters. I am not sure if their design is open source or not though.