My Touch 3g Battery extender on the Sprint Hero? I live in NYC and on 34th street between 6th & 7th avenues there is a T-Mobile store right next door to a Sprint store. At eh T-Mobile store i saw an accessory for the My touch 3G called a battery extender. It basically plugs into the bottom of the phone making it longer and is an external battery. Have any of you tried this accessory with your Hero? Does it work?