With the open-source database market split between quite a few contenders, the ones who are not at the tip of everyone's tongue need to find ways to distinguish themselves.
Ingres - the once closed-source database that was spun off from Computer Associates a few years back - continues to aim for the high-end corporate market. Their latest move in this strategy is the release of substantial portions of their
OpenROAD 4GL as open source under a GPL license.