Pretty much. 802.11 B and G run at 2.4 ghz, and have 11 channels, though only room for 3 without overlap. 802.11 A runs at 5ghz, and has many more channels, but never really caught on.

802.11 N allows operation in either 2.4 or 5ghz range, and a dual band router can run in both at the same time. This allows for someone to keep legacy B/G devices around while also migrating newer devices to N in the 5ghz range. N also allows 2 channels to be tied together for higher speeds, and this is where having the 5ghz frequency helps. With more channels, it's much easier to find 2 without interfering with someone else's router.

As others have pointed out, you really won't see any benefit from an N router currently, and definitely not a dual band one.

As for Wake on Demand, it's a feature Apple systems support with Snow Leopard. Basically it allows a machine to go to sleep, and still have the network services it provides show up on the network. IE, if I have my desktop setup to share files to my laptop, my laptop always sees the desktop on the network even if it's asleep. If I try to connect to the desktop to grab a file, the desktop comes out of sleep mode. The really convenient thing for me with this setup is that it works over the internet as well via Back to my Mac. So I can click on my home desktop from my work machine, and grab files even if it was asleep. There are other ways to achieve the same thing, but this method is completely seamless. With the whole move to green datacenters, I wouldn't be surprised to see something similar there in the coming years. File servers could enter sleep mode when everyone has left the office, but come back online when someone needs a file the next morning, all without manual schedules or additional programs needed on the client side.