Update 1: iOS 5 Final version has been released for Download and Jailbreak - Click Here
According to sources inside Apple, that Apple developers are working hard now to implement new feature on the upcoming iOS 5. Precisely , iOS 5 will allow you to read your voicemails by translating them into text.
Google Voice already does the same job by translating voicemails to text, so that it makes sense if Apple wants to stay competitive in the cloud space. So far we have no idea how will voicemail transcription looks like in iOS 5.