Glad to see you found the forum ;-)
"what is [Overlord]?" Well I assume you read the project page and associated pages and still didn't find an answer? Well if you hold for a few more days I'll have the complete roadmap outline done, but in the meantime "it's doing SOA governance" ;-)
Sorry, couldn't resist.
Seriously though, at the moment the project is pulling together partners who can help fill in some critical pieces (e.g., CDL work), whilst at the same time fleshing out an architecture that includes both design-time and run-time aspects of governance. This will impact on some of the projects within our SOA Platform (or community version, JBossESB) and in that regard Overlord will act as the driving force for unifying approaches (e.g., service contract definitions, SLAs, repositories) although it may not provide any specific implementation code within the project code base (e.g., repository, which will be based on DNA and Guvnor).
Feel free to shoot more questions. But the roadmap doc should be ready soon. Anything you suggest/ask now may find its way in there (or help clarify it prior to release). As ever, all input is useful :-)