Open source software is software that is free. Free as in no cost to obtain, and free as in freely modifiable.

A screen shot of the software can be found here.

From the author:

A decent portion of Home Automation spending seems to be going to HomeSeer (HAL, etc), Plug-INs, and controllers. I feel like the HA field would advance much faster if there was an open source movement behind it. It would make automation cheaper and allow more people to influence the design of the software.

My HA app is graphical, Windows based, Drag and drop interface, House maps with multiple floors, database driven... Just click on any motion sensor to simulate movement, great for testing. Click on any light for control, click on any speaker to activate it (AB8SS).

If you are interested, stop by the CocoonTech forum and let him know.