Yes, that has been confirmed and, again, 1GB of RAM would have resulted in far less battery life. A Microsoft employee has recently blogged about how the increased RAM on their phones would have severely reduced battery life as the RAM has to be kept active even when not in use.
Apple is very deft in making sure they can keep the battery life up while still providing an extremely enjoyable user experience and acceptable speed (in fact, much increased speed in this device over the iPhone 4). Remember, it's about the total user experience, not individual specs.
It will likely be possible, through jailbreaking, to increase the clock speed. But, this will be at the expense of reduced battery life. Furthermore, once you see the speed of this phone you likely won't see a need to increase the clock speed.