Pretty cool. I've become interested in this topic when I read the paper on Natural Language Query System for RDF Repositories[1], which mapped NL queries to a PIM ontology using SPARQL, but alas, I never further explored it.
It's nice to know the technology is becoming available to the average programmer like myself ;)
You can certainly go a long way with pretty naive models that take advantage of RDF[1][2], because you can just match words in a query to those in the ontology. Our model is a little more complicated, as we need to support everything from simple things like 'not' to negate part of a query, to more complex stuff like 'more recently', and compositional queries (what products have sold more than products that are red, tricky stuff like that).
It's nice to know the technology is becoming available to the average programmer like myself ;)
[1]: http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.115...