No current Sony models use DVI. New models with DVI (including HDCP) start arriving in May or June according to Sony's schedule. DVI w/HDCP virtually guarantees the the display will work (at full hi-def resolution, through its digital inputs) with whatever copy protection technology comes down the pike for the next ten years or so.
If you do not buy a display with this technology (or DVLink, aka firewire w/DTCP), there is a chance that at some point in the future, studios will choose to release protected hi-def content that your display won't be able to show at its full hi-def resolution. (Your display will not be considered "secure" because it doesn't have an encrypted digital interface.)
As a practical/legal/financial matter, it's hard to believe that this will happen during the next five years. At the same time, one cannot ignore the fact that today's copy protection schemes (DVLink, D-Theater and DFAST) enable this level of security.