An infrequently-updated but informative blog on open source BPM:
We share our discoveries in our search for open source workflow management tools. For tools that we find interesting, we download the code, try to execute the engine, or even get our reference process model working.
Also includes a list of open source BPM tools, including their evaluation notes where applicable.
Note that these are the only two sections of the site in English; for the rest, you’d better brush up on your Dutch (or use AltaVista’s Babel Fish translation utility, since Google’s translation doesn’t support Dutch).