There are several places where protective bumpers always belong: cars, children's bowling parties, and electronics cases.
Rubbery corners are a trademark feature in Ballistic's cases for a variety of smartphone makes and models. In its most recent line for the iPhone 4 and 4S, the Ballistic LifeStyle Smooth series, the case-maker brings the silicone inserts to a fairly fitted design for Apple's iconic phone.
How does the $30 case fare? Pretty well, actually. Check out the photos, the pros, and the cons in my full review of the Ballistic LifeStyle Smooth case, which will be available to purchase very soon.