Developer Program for Viewing Passbook-Related Pages
Yes - those links are pre-release and protected to iOS registered developers. You might get by with an educational account - but most developers use the $99/year plan to gain access to the Provisioning Portal.

Provisioning devices for testing your application on real iPhones rather than the simulator does require a membership, as does any pre-release software or documentation. However, Passbook is not pre-release documentation any more; with the release of iOS 6, they have published public documentation, so you can view this. If you need more information as to what the $99/year membership gives you access to, view their iOS Developer Program page.