It still seems fairly untapped in enterprise and entrepreneurial circles, too. I've been wanting to create a side project that is sort of like an expert system,

It still seems fairly untapped in enterprise and entrepreneurial circles, too. I've been wanting to create a side project that is sort of like an expert system, except where users can create the rules as well as the facts, and that is also horizontally scalable (which doesn't seem to be a good fit for the Rete algorithm). So I'm not sure if I'm looking for some sort of jvm-runtime logic programming system that can be combined with a graph database or what.