The new iPhone will be unveiled later on today, but before that the latest rumor is that the iPhone 6S will feature a new 'always-on' Siri mode. This new mode will be similar to saying "OK Google" on an Android phone, so you won't need to press the 'home' button on your new iPhone 6S to get Siri sprung into action.
9to5Mac is behind the rumor, adding that Siri has, until now, only actively listened to you when your iPhone was charging as it was a drain on battery. But with iOS 9 and the new iPhone 6S, this might become a thing of the past. It definitely explains all of the hoopla surrounding the 'Hey Siri, give us a hint" banners that have been popping up around the place.
The new iPhone 6S will reportedly also be thicker than the current iPhone, but we will know all about that later today.