PowerVu is pretty old, and (at least in the USA) it's not really used for home viewing, so I think this isn't very interesting unless you have a giant C / Ku band antenna.
Right. But if you do have a big ugly dish (or are willing to find one on the free section on craigslist and put it in your backyard) you can theoretically view nearly everything.
PowerVu isn't used by DirectTV or Dish for their home viewing. But it is still used by the major networks. Nearly everything from sports to entertainment is on PowerVu at some point, and then received and retransmitted by individual carriers.
My experience working in cable headends are that most programs that we watch on cable are delivered using DigiCipher (motorola's) CAS. There are always one or two PowerVu receivers tho: Viacom (MTV, A&E) is one notable feed. Also there are usually a small number of tandberg-style receivers with Irdeto or something.
Nevertheless I was glad to see that someone is figuring out PowerVu :) I would like to see the same for DigiCipher, as the 4DTV scheme uses it.
Both PowerVu and DigiCipher have similarities to the CAS schemes from their respective manufacturers for cable settops, too.
[1]: http://colibri.bplaced.net/powervu.htm