This whole idea seems a little outlandish, even for Microsoft. What executive could possibly think they would sell more Zunes from having NBC content available then they would lose from people who couldn't put their own media on the device?
Note that /cash/ is crucial when talking about a anonymous transaction. In a cash transaction, after a sale completes, the honest seller has essentially no exposure beyond, say, a warranty return. If you payment is instead made in some way (credit card, paypal, etc) where the seller is on the hook for fraud, things start to suck hard. Unfortunately, no governments/banks like totally anon ecash, for national security reasons (e.g., funding terrorism).
There are certainly ways to make credentials that are not easily recreated. One example, although perhaps not the best, is to send a text message to a cellphone number.
http://zuneinsider.com/archive/2008/05/07/just-so-no-one-get...
This whole idea seems a little outlandish, even for Microsoft. What executive could possibly think they would sell more Zunes from having NBC content available then they would lose from people who couldn't put their own media on the device?