I just discovered this nifty little “trick” in iOS 5. While making sub- folders from the camera roll, you can hit the top right button, which allows you to select individual pics for different functions, i.e. tweet/ email, and move them around in the order you like. Much in the same way you move apps around your springboard. This can be very convenient, especially if you have a few racy pics you don’t want as the sub-album cover. 
Apple has done a nice job of allowing you to organize your photographs, which is nice, now that the iPhone 4/4s camera is good enough to be most people’s only means of taking a picture. And when iOS 5.0.1 is released with the ability to delete pics from iCloud’s Photo Stream, the last piece of the camera roll puzzle will finally be in place. Happy shooting!
