Virgin Mobile is offering the iPhone to its prepaid customers as of today. The Sprint-owned subsidiary is using the event to kickstart a new retail strategy that will see the company open branded retail stores in Chicago -- with a nationwide rollout dependent upon its success. Since all carriers have to make a minimum commitment to Apple in order to receive the handset, it's interesting to see that Virgin's allocation forms part of Sprint's $15.5 billion gamble on the handset that's still yet to
