I've been using Cfengine 2 for a number of years now, and it's a great configuration tool. They've recently put out version 3, and the changes are... extensive. As in, Java vs. C++ extensive.
I'm very tentatively trying to move over to 3. Yesterday, they put a big help up on their website:
Now on line at our Technical Corner is a conversion sampler, that
enables you to perform a limited conversion of portions of configuration
from Cfengine 2 to Cfengine 3. To convert larger samples more
completely, you can arrange professional services with Cfengine AS/Inc.