According to 9to5Mac, Apple’s most prominent carrier partners have been seeded "near-final" builds of iOS 5 for final testing. But these builds are different from other seeds before, this build come with the Nuance's Speech to Text as a system-wide service:
"According to a source testing the feature, it works almost identically (video bellow) to the Android operating system’s speech-to-text feature. It’s also very polished, quick, and accurate said the source – which is obvious for being an Apple product but also is indicative of the product being nearly complete."
It is said there will a microphone button that appears next to the spacebar hidden in the depths of iOS 5. This presumably allows users to dictate rather than type. Android has a similar system already implemented, as seen in the video above.
Reports of Apple's ongoing negotiations with Nuance date as far back as May, with some claiming it was still coming in iOS 5. iOS 5 is due for public release "this fall".
If all true, Apple must be planning on launching their Nuance dictation system alongside the public release of iOS 5. Some source says this service might still in developing, but it would be a suprise if it appeared on the Apple's conference which is widely thought to be on next month.