I'd love to see Twitter become a "command line of the web". Add voice integration on top of it via siri/google/etc, and it come become the plaintext glue between a lot of services.

What we have here is a pub/sub message transmission layer that just happens to be used by a lot of people for personal communication. Having machines use that for other things is something that's already been experimented with - using it as a de-facto API layer is a logical step.