I don't have the hardware to determine if this is a true master key or not, but the implications are huge. If this is a true master key, HDCP is broken and DRM has, once again, failed. You can create your own keys that will never be able to be revoked. Essentially, you've made HDCP into DVI+Audio+Breakable Encryption.
If this is true, it means a whole host of new features that have been denied to paying customers. MythTV might actually be able to hook up to a HDCP source for input instead of doing the component capture and re-encode. There are a wealth of fair use cases that just opened up. This has to be true, though. Can anyone confirm that this master key is legit?