Very interesting. They have other tools which are rather useful looking as well: http://pybee.org/ (debugger, test runner, coverage visualiser etc)
Of those tools, the test runner (cricket) is the most mature; the debugger isn't much more than a proof of concept. Those tools are also based in Tkinter at the moment; I started Toga because I've started to hit the limits of Tkinter.
The intention is to port the other PyBee tools to Toga as soon as they get mature enough.