MS research is working on an HyperGraph database.
Here is the link: http://research.microsoft.com/en-us/projects/trinity/.
Trinity is a graph database and computation platform over distributed memory cloud. As a database, it provides features such as highly concurrent query processing, transaction, consistency control. As a computation platform, it provides synchronous and asynchronous batch-mode computations on large scale graphs. Trinity can be deployed on one machine or hundreds of machines.
My guess is that Semantic Networks will become more and more important in the future. We will go from a Web of Data to a Web of Information, and the semantic aspect is key here.
Needless to say, RDBMS are not well suited for graph management.
Object databases could be more relevant, but there is no doubt that specialized databases like Trinity could bring something.