HandsFree is a recently released jailbreak tweak that works in conjunction with iOS 7's Phone and FaceTime apps and introduces the ability to answer incoming calls straight to speaker with a simple wave of your hand. The key phrase here is "straight to speaker," as this tweak eliminates the two-step process previously required to answer a call and enable speakerphone.
HandsFree works with FaceTime Video and Audio in addition to cellular calls, so answering an incoming call is seamless across the board...