The folks that gave us Air Display have just released a 99-cent app called Air Dictate. This app lets the user enter text in any text field on a Mac system, by speaking into the iPhone 4S. Once Air Dictate is installed on the iPhone and the receiver app on the Mac, the two devices can be linked for easy text entry by speech. Both devices must be on the same Wi-Fi network to link.
How does Air Dictate use Siri to convert speech to text?
Apple expressly prohibits developers from using private Application Programming Interfaces (APIs). And, there aren’t any public APIs enabling Siri to take dictation. Avatron programmers, independent of Apple, have devised codes that empower Siri to automatically convert speech spoken into an iPhone 4S into a Mac’s text field, just as if it was typed on the computer’s keyboard.
I have tested Air Dictate and it is pretty good at accurately converting speech to text. It is not perfect, but can be a viable input method for 99 cents.