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.
The exact definition of 4GL has been a matter of debate, but generally speaking tools that are optimized to quickly crank out "line of business" applications fall into this category. OpenROAD fits here: it's designed to hook up an Ingres database to a user interface through the use of objects. What distinguishes development environments like OpenROAD from more general IDEs is their focus on letting you work as much as possible in the business realm instead of with the nuts and bolts.
Traditionally, 4GL development has been viewed as less than exciting by much of the development community - though it's been a source of great revenue for firms that have specialized in banging together business applications quickly. By open sourcing its efforts in this area, Ingres is obviously hoping to combine the benefits of open source with the need of consultants to pick a language. For example, the fact that OpenROAD cannot now simply vanish makes it a more viable choice for firms that are figuring out what to bet their future existence on.
Interestingly, Ingres is not just opening its own code here - it's also working with some of the other companies who have developed OpenROAD enhancements to get those opened up as well. This is a new twist on putting together an open source community: convincing your business partners to come along, in the hopes of attracting more end users. As with its other products, Ingres offers a commercially-supported version of OpenROAD as well, providing a clear upgrade path for developers who decide to learn this tool - as well as a revenue source for the company.