Well at least here’s one, although only for the iPhone – ShoutOUT by Promptu. It takes your dictation via the mic and converts it into text. You can use it for your SMS messages, Facebook and Twitter updates, etc.
The app itself is free, and the first 25 voice messages are free. After that, you pay fees as follows:
50 for $1.99
150 for $3.99
250 for $4.99
Price: free (for the app)
(Please note prices are subject to change and the listed price is correct to the best of our knowledge at the time of posting)