I joined the digital TV revolution yesterday with the purchase of a Vizio 37" 1080p HDTV. So far we are quite enjoying it. One issue that is still ongoing is that the TV's remote overlaps with the DVD player's (which we are also using for the MythTV). When you push the Zoom, number or volume keys you get more than you bargained for.
But that issue is ongoing. The one I'm writing this post about has been solved, thanks to a mythtv-users post I came across. The symptoms were that some video, for me it was anything on CBS or ABC but curiously no others, would be really shaky. It was almost like an interlaced shearing effect, but not so regular or consistent. I played with the interlacing options and output drivers to no end. Finally I came across the above thread and discovered the problem: a bug in the nVidia kernel driver. I simply upgraded to the latest version and the problem went away. This is a very good thing.
Otherwise everything about the MythTV setup has worked well in high-def. I just had to add a "1920x1080" mode in xorg.conf and then do the same in MythTV. I later adjusted MythTV to use fullscreen, regardless of the resolution, which is what it should have been in the first place. I was worried that it might take some major tweaking to get widescreen or high-def or who knows what else, so overall I'm very pleased.