Apple’s Siri and Nuance-powered “Assistant” voice control feature expected to launch with iOS 5 has hardly been a secret, and now MacRumors has commissioned a video mock-up of the service based on what we know so far. The video shows, for example, that a user might be able to hold down the home button to activate the application and speak a command, not unlike Apple’s simple voice controls today. Assistant should step today’s capabilities up quite a bit, however. The service will likely scour your phone’s contents or the web to deliver results, and it may even be capable of replying to you; in the MacRumors video, Assistant asks the user if he would like to text a contact’s mobile or work number. We expect to hear more about Assistant during Apple’s iPhone event on October 4th. Read on for the full video.