I really don't want to have to pay for international calls to request new features... But even the fact that they listened to your request is very encouraging. The ability to choose between dictionaries on the reader is already there, I don't see what is stopping them from making more available. I wouldn't expect them for free, and they couldn't possibly install all the different languages that people might want, but having the option to pay for and add to my reader a third-party dictionary of my choice would be great!
Can someone direct them to this thread?