Milo Winningham
There should be one soon, according to this post. I'm anxious to hear about it as well.
On a similar subject, I recently received a new update to the spec which defines a new security and permissions model separate from AACS. I think this new model could make the testing of FullTrust-mode content easier.
The new system allows content to be signed by any certificate authority (not just the AACS LA). Of course, players will only accept content signed by a trusted authority. But the spec mentions that players can optionally allow users to control which publishers and CAs are trusted. This sounds like a good compromise to me.
Some speculation by me:
One possibility is that a player could allow applications with a certificate that was signed by a regular CA like Verisign. This would prove the identity of the publisher, but not the trustworthiness of the content, so the player could then ask the user if it should trust the publisher. Applications with a certificate signed by a HD DVD-specific CA could run without any prompts (like in the current security model), because in this case the CA would verify that the application is not malicious and create the certificate themselves.
Another option would be for player manufacturers to distribute a special "testing certificate" to developers to allow them to sign their applications for a specific player.