The first beta of iOS 5.1 has been seeded to Apple developers, and includes several changes and improvements. First off, code has been uncovered pointing to support for a new piece of hardware, namely a Sprint iPad 2. Apple launched the iPhone 4S and iPhone 4 on Sprint's network just recently, and it appears they are taking the next step.
Other changes spotted by 9to5Mac include a new setting in Location Services for geofencing. One source of battery drain is geofencing, when an app such as Reminders puts a virtual perimeter around a location. Notifications are sent when leaving or arriving the location, and in iOS 5.1 each app that uses the feature has a special icon in Location Services.