For those of you wondering whether or not old Time Capsules and Airport Extremes would get the new Time Capsule and Airport extreme functionality, we have some good news and bad news. After updating to 7.4.1 we learn that Apple has given us one out of three.
The bad news is that guest networking and dual band support aren't available. It looks like that is a hardware-only update (meaning you'll have to buy a new one).
The good news is that if you have MobileMe and use Back to my Mac, you'll be able, as of the 7.4.1 update, to access the data on your Airport Extreme USB Drive or Time Capsule over the Internet. Visit Apple's page on the updates for all of the juicey details on update 7.4.1.
