The AACS or Advanced Access Content System is the consortium behind HD DVD and Blu-Ray's content protection.  Companies making hardware to playback these formats must play ball.  Last week the AACS came to an agreement about downrezzing, a longtime bogeyman of videophiles.

Basically downrezzing is the act of downgrading (down-sampling) video signals from an HD playback device's analogue output.  Analogue or component video outputs on your new HD DVD or Blu-Ray players had been the focus of downrezzing rumors because content cannot be regulated through it.  Pirates can theoretically make unlimited copies from an analogue source so HDCP (High Definition Content Protection) was created to protect movie studios properties.  Your non-HDCP compliant video connections (IE component) are liable to be downrezzed on HD movie discs.  So, instead of getting full blown  1920 x 1080 resolution (up to full 1080P) from them you'll only get 960 x 540. 

The feature (explained at VideoBusiness.com) on the new movie discs is called ICT, (Image Constraint Token) an embedded digital flag that can be turned on or off at the studios discretion.  Studios choosing to downrez their video release to an HD disc will be required to warn consumers on the packaging that this copy will be down-sampled from an analogue source.

So far no studio has stated how they'll respond to the ICT option but there are rumors.  Warner is likely to enforce downgrading video quality on its releases because it had been the strongest proponent of the measure.  Its likely 20th Century Fox and Sony will tend not to use the ICT because they have argued against such measures in the past.

It's just another example of legal constipation of technologies progress.  It's an inherently flawed philosophy that may one day be the downfall of mankind.