My Natural Language Systems professor just went through that topic yesterday -- that in the case of all machine translation applications, the ultimate goal is to get as high up in a 'natural language pyramid' where the tip is a single universal language. So we get the most use out of elements of any two given languages that have as much in common with each other as possible; these common elements could then be applied to other similar languages.

Interestingly, he also proposed that the closest thing we have right now to that 'tip' language is sanskrit.