Yesterday, evidence of more voice recognition features in the most recent iOS 5 beta came to light. 9 to 5 Mac posted this image showing a small microphone button in a hidden iOS 5 keyboard, indicating that it might be possible to dictate text vocally to your iPhone instead of entering text manually.
If this feature does get fully fleshed out and released with the gold master of iOS 5 or a later version of iOS, it will definitely do away with my need for Vlingo, a voice-to-text app I currently use for hands-free text messaging. And I bet Vlingo is not going to be happy about that.