In addition to the new Mac Minis & iMacs, Apple also introduced a new Airport Extreme Base Station & Time Machine today. The new base station adds two very appealing features: the ability to use 2.4GHz & 5GHz bands at the same time, and ability to set up a guest network for internet access only without being able to access other machines on the local network.
I usually let my “snowbird” neighbor use my wireless network when he’s here, which is usually for a week every few months. I would feel a lot more comfortable setting it up without access to my local network, so I’ll probably get the new base station for that feature alone.