Siri is a terrifically useful app. Basically, you ask it a question like "nearest cheeseburger" with your voice or by typing. It then notes your location, scours the web and returns the best results. I've used it out here in the middle of nowhere with much success. The speech recognition is quite good. It comes from Nuance, the company who's software powers both Dragon Dictation and Dragon Search.
What will Apple do with it? Essentially, it's a mobile, location-based search engine. Steve Jobs recently criticized Google for "...getting in the phone business." Does that mean Apple is getting into the (mobile) search business? Perhaps the technology behind the application will appear in a future iPhone update, perhaps as a standalone app. We imagine it could be a part of the next-generation maps application.
Congratulations to the Siri team.
[Via Robert Scoble]