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. The bad news is that guest networking 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.
It would be really kind of non-douche-baggy of Apple to allow non-MobileMe users to use Dynamic DNS from the Airport, instead of making people shell out $100 for this capability. We aren't holding our breath.
