You would need to have precisely defined concepts from standard English in genera/differentia format in such a way that the system could determine contextually which concepts are being used in the user's query, and with that you could execute whatever you wanted. The differentia would have to be framed in a logical format, preferably using Fred Sommer's Term Functor Logic (dramatically superior to First Order Predicate Logic. This is the problem our startup was first working on last September (we started research for this in 1997 - we are deploying a very "lite" version of this in our new application).

The biggest barrier to solving this problem is the difficulty of formally defining English words. It took us several years to figure that out (with the Epistemolgy Aesthetics Study group and heavy reading of Aristotle's Organon) and we ultimately found that definition through an inductive approach was key to success. There will come a time in the not too distant future that people who can correctly define concepts will make serious money.