I don't now if the iPod Touch 4G is special or if manufacturers are just slow to update their web sites but it looks like there is a dearth of compatible ext. batteries for the iPod Touch 4G. Everything I see says its for iPhone 2G/3G. Can someone give me some suggestions for a good ext. battery -- something portable, preferably that attaches to the Touch vs. a battery block w/ a dock connector cable. It's for a gift so I need to be certain it works for the 4G.