A few random comments/responses:
Re: 4:3 and anamorphic
Just because you get black bars and the picture extends to the sides does not mean your TV does anamorphic widescreen. If a DVD player is set to 4:3 Letterbox, widescreen movies will display this way. The TV must be capable of doing the so-called anamorphic squeeze, which will look the same, but have higher resolution. If your set has component inputs, it might work. If not, you're probably hosed.
Re: HB going Leopard only
I have not upgraded to Leopard yet because my dual 800 Quicksilver isn't supported. Yeah, I know there are ways around it, but I'm getting ready to upgrade to an 8-core MacPro, so I'm waiting. In the meantime, I'm not encoding any DVDs yet because they take too long on my computer. And this gets me to my point: I would be willing to bet that most people who have not upgraded to Leopard are running machines that are at least a couple of years old and most are probably not the kind who would wait a half-day for a single encode anyway. I suspect that the vast majority of people who are doing this and own AppleTVs are running Leopard.
Misc
I'm dying to get my new MacPro and start encoding some DVDs to load up, but my present situation won't let me for a while; I'm on an extended business trip (heck, I haven't even had the chance to upgrade to Take 2). When it all comes together this summer, I plan to go to town so I don't have to, uh, go to town...
I've been following this forum for a couple of months while I researched AppleTV and now while I research HB and other aspects, so I'll be smart when the time comes. I ordered my AppleTV on the day of the keynote (pretty much as soon as Steve Jobs made it clear that the device has a future) and I love it. Even my wife loves it. Can't wait to take full advantage.