It may be a little bit longer before you are able to get your hands on a HD DVD version of Firefly thanks to Blu-Ray. The specifications for the AACS (advanced access content system) have been delayed because of a extra anti-piracy measure that Blu-Ray is using, called BD+. BD+ is a dynamic encryption scheme that lets the Blu-Ray group change encryption schemes at any point. This is being used to prevent one specific crack from working on all Blu-Ray discs. The delay on the AACS specifications is expected to last a month.
HD-DVD and Blu-Ray Delayed Again Because of Blu-Ray [eHomeUpgrade]