AT&T Has proven speech to text. Their goal is to allow developers to integrate this technology into their apps. This demo is done on a Blackberry but at the show she had an iPhone and an Android device running these same features. Once iPhone has multi tasking it will be able to run in the background.
Now that a lot of states are instituting strict cell phone laws, this type of technology will really find a home with all kinds of developers.
Check out Vlingo's blog If you want some serious detail on the matter.