It's all still composed for 4:3 NTSC.
I was watching Gonzaga v. Indiana and Xavier v. BYU tonight for March Madness and I had to hone in on a small, 4 by 3 region in the middle of my big 42" HDTV to really see the action. This is not a problem with shows and movies originally composed for letterbox, but it is a problem for sports and original TV shows. Sports on HDTV let you see more of the field and the crowd, not the action. Why?
Well, the electronics manufacturers sold broadcasters on HDTV with the following premise: "You can use the same camera for both your NTSC and HDTV broadcasts. Just put marks on your camera so you compose for 4:3, then extract that middle region out and send it to your NTSC antenna and send the 16:9 picture to your HDTV antenna." Only problem with this strategy is that your HDTV viewers end up getting 33.3% more of the crowd, football field or basketball floor, not of the game. Furthermore, since these broadcasts are in 720p, I get a 960x720 image of the action. I guess that's 50% more pixels, but it still effectively makes my 42" plasma into a 34" 4:3 screen. What's the point?
Moving beyond sports for a second, I have maintained for a long time that broadcasters would have been better off sticking with 4:3. 4:3 is the radio of the gods, after all. The pyramids were built with it. Widescreen is a gimmick that the film business has stuck with for far too long. All joking aside, widescreen makes it impossible to compose anything other than the long shot or the extreme closeup. This is swell for westerns and movies like "Lawrence of Arabia." It doesn't work so well in your typical movie. Ever notice how we never see the tops of anyones' heads in the movies? That's because composing a mid shot on widescreen looks absurd. There's a bunch of wasted space on either side of the subject. So you have to push in close to the subject and cut off their hair.
If you don't believe me that 4:3 is much better for composition, take the practices of one of the world's greatest filmmakers: Stanley Kubrick. Did you know he only shot one film in anything other than Academy (4:3)? It was "2001: A Space Odyssey", which was shot in Cinerama. You may have noticed this because when you buy his movies on DVD, they thankfully have reproduced them in full aperture, which is what they were intended to be. Contrary to what you might think, his movies are not pan and scanned.
Take, for example, Eyes Wide Shut. Look at the composition of these shots and imagine how they wouldn't work in widescreen.
BTW, I randomly popped in this DVD and picked scenes from it. It should be apparent to you how the composition is stronger with 4:3, but either way you should see the movie if you haven't. As my old co-worker Albert Hastings once so eloquently put it, "You could take any frame of this movie, blow it up, and hang it on your wall."
Back to broadcast HDTV... basically if you buy HDTV to watch sports, you're getting screwed. They're not going to frame the sport so you really get more out of it than if you were watching good old 4:3 NTSC. Personally, I blame Sony for this situation... but that's just me. I wish they would have stuck with 4:3 for HDTV.