I saw an article about this on Wired yesterday. One of the first comments was someone talking about how a Netflix movie was ~3GB. What went through my mind at that moment was(directed toward that commenter) "Looks to me like you're a big part of the problem".
Seriously, it's a frickin' PHONE. Netflix streamed movies are, in my experience, complete garbage quality-wise, but maybe it looks OK scaled down to iPhone-size. Still, it seems to me that people are getting carried away with the whole iPhone craze.
Disclaimer -- I do think the iPhone is pretty neat, and I'm anticipating a price drop on the 3GS when the v4 launches on Monday. Yes, I want one. All of the folks that I talked to about the early iPhones told me that as phones, they sucked -- "but look at all the other neat stuff you can do with it". As I understand it the 3Gs is the first one that actually works well as a phone, which -- believe it or not -- is the primary reason that I own a cellphone.
Back to the topic at hand, maybe this new policy will in effect slap some sense into Netflix and hopefully some of the abusers. If Netflix were smart, they would offer a way to download the movie into the iPhone via computer or WiFi. For the people who just HAVE to be able to pick out and stream a video on the spot without any foresight or planning, I have to wonder what they did 3 years ago... was their life completely devoid of meaning or joy before they were able to stream Netflix videos to their phone via 3G? Is their world going to collapse around their ears now that there is a penalty for doing so?
Several people at work constantly check business email via iPhone, use Google maps, browse the web occasionally, etc. and come in at 200-400MB/Mo. I doubt that I'll need over 2GB/Mo but I'm prepared to come back here and eat crow if that turns out not to be the case.
I know that my opinions may be in the minority on this, but IMHO it made sense for AT&T to do something about the problem. If everyone tried to stream Netflix vids at the same time it would bring the network to its knees. Obviously AT&T needs to increase capacity, but even if they have the will to do it that's going to take time. As someone who has worked in datacenters for a very long time I think it makes sense to throttle demand a bit until they catch up on infrastructure.