Here are a couple tools that might be of interest if you are looking for open source configuration management and/or CMDB solutions.
Update: someone noted that there is already a Wikipedia article on this. So I'll probably not keep this alive.
I'd note that most of these tools appear to be sysadmin element management focused on the most common platforms; no Tandem, iSeries, or mainframe. They do not appear generally to be concerned with enterprise configuration management in the sense of maintaining accurate inventories and interdependencies, nor do I see direct integration with Change, Incident, Problem, and other processes. Not sure if they do much for the DBAs, either.