The latest update for iOS, 6.1.2, is now live for all devices. The update fixes an Exchange bug that was affecting networks and battery life. But unfortunately, the update does not address a recently discovered hack which allows anyone to access your iPhone despite a passcode being set up.
Apple released iOS 6.1 this afternoon, adding 4G LTE functionality for a large number of global carriers. Beyond the cellular improvements, iOS 6.1 offers some minor tweaks to Siri features, controls, and privacy settings.