There are a ton of different ways to approach the problem of interpreting a command. if you're interested in a solid reference for computational linguistics, then i recommend either 'speech and language processing' by jurafsky et al or the 'oxford handbook of computational linguistics'. finally, the forthcoming information retrieval book (http://www-csli.stanford.edu/~hinrich/information-retrieval-...) is a fantastic resource.

however, keep in mind that a lot of the stuff in these books has been used more at the academic level than in commercial applications. we at wundrbar are being very careful not to bite off more than we can chew. many companies have tried and failed to tackle natural language processing, and we are NOT doing that; we feel like we can add a lot of value without trying to do anything too fancy. our commands right now are identified by keywords located at the start of the command - simple, intuitive, reliable.