RUNA WFE is a open  source core for a commercial product
you can get training support, manual, etc by paying to developing company.
you can find  their web site in:

http://www.runa.ru/
http://wf.runa.ru/

you can find some documentations under:

http://wf.runa.ru/English/Docs/Docs.html

be careful wf.runa.ru is GPL
it means you have to open source  the product you want to use RUNA WFE on it.

if you just want a good workflow  engine and WFMC compliance is not important for you, we are working on YAWL, it is a good open source engine, and I can help  you to use it.