So assume you have an iPhone 4S. Siri, the new voice activated assistant, can do all kinds of cool stuff, but it's sandboxed to the Apple-created uses. There is currently no public API... sort of.

Siri can send SMS messages, and SMS looks remarkably like a messaging queue. Given that, you have a basic messaging queue hook within Siri. So if your receiving endpoint happens to be an application, rather than another mobile phone, you need only to parse the input and take action.

This will not reach widespread adoption, however. The integration is too loose, IMO.