EnterpriseDB and *cough* Open Source
EnterpriseDB is not, never has been, and likely never will be Open Source.
Yes, the core is open source, but the parts that make EnterpriseDB != Postgres are all closed source.
Strangely enough, the marketing folks at EnterpriseDB always forget to mention this. They do make sure to say "Open Source" at least three times in every press release, tho'