Open source ERP

A couple weeks ago, I asked to hear from anyone who knew of a truly open source ERP system. I didn't get any responses, but I did come across a research note by Paul Hamerman of Giga Information Group on Compiere, which appears to fit the definition. Compiere's license agreement, which is modeled after that of Mozilla and Netscape, provides source code to users at no charge. However, the product is built over the Oracle database, and Compiere is an Oracle database reseller. So the company evidently is giving away the Compiere source code and pulling through Oracle license sales as well as training and implementation. It's an interesting approach, although one would imagine that companies looking for "free software" would be reluctant to turn around and buy Oracle database seats. I also wonder how many small and midsize firms, which would be the natural market for Compiere, would be willing to invest in the requisite effort to keep up on patches and fixes. The whole open source movement, to me, makes more sense for operating systems, tools, and utilities, which can leverage a much larger development community. It would seem that the higher you go up the technology stack toward complex business applications, such as ERP, the more difficult the open source model would be to sustain. I would like to be wrong on this one, but I'm still waiting for an "existence proof."