The difference between the old CRT and a new HDTV is the CRT won't have component inputs, and can't deal with progressive signals. I wonder if with the digital switchover Apple threw in an upgrade to 480p over composite, which no older technology would know what to do with.
You're a bit off on a couple of facts. First, component signaling has been around since before LCD screens were invented. Second, I own a CRT television with component inputs, and my Apple Component AV Cable worked just fine for connecting my original EDGE iPhone to my TV. And lastly, while you're correct that Apple has changed the iPhone 3GS to 480p output (previous iPhones put out 480i), it's something they had actually already done with the iPod Touch.
Now, it does seem that you're right about the CRT not being able to handle the 480p signal. But that doesn't make much sense, because the iPod Touch has always put out 480p. and it's only now that it's stopped working.
Anyway, I just bought a second-hand HDTV today, and the 3GS puts out video beautifully on it. Still no go with the CRT, though, using the same cable.
Do the 'official' apple cables still work ??
You gotta read the thread, yo.