Hi,
Caroline had shown some interest in the P/O forums, so I've put up some developer and design documentation at http://www.project-open.com/product/dev_doc/intranet-forum/ (I've check the link this time...).
The comments in the code still say that it's a proprietary software, but we've decided to make it GPL. We'll update the code and the web site soon.
The package requires the Project/Open "Core" module...
Bests,
Frank