Requires iOS 7 or higher.
Requires Dictation capability.
"Type and Talk", derived from a method name existed in Apple iOS 7+ UIKit API. It is about how Dictation activation will be. Apple disabled this feature by default.
As user tap on dictation icon on the keyboard, there is no an overlay view with wavey animation anymore. Dictation is still listening, but you still can use the keyboard to type text at will. When you tap on the dictation icon again, all recognizable phrases will be inserted in the current text view just like normal.
To sum up, this feature allows you to use keyboard while using Dictation.
Open-source tweak: on Github
Configure directly from Settings > General > Keyboard > Type & Talk