60Gig cap here, 2 comps on WoW most evenings, a third on some Steam account, or Unreal Tourney or something. That doesn't even included normal online activity, laptop in the kitchen activity, or XBox live activity. Never touched the cap. I know some people here talked about streaming HD over the INet, but why? I just learned to watch HD channels and watch HD movies and the like on my 52" HD TV where bandwidth is not an issue.
edit:
Mathamatically, lets assume you use the internet the same way I do, and use all 60G of my alotted use per month, that means you still have 190G left for extra-cirucular use. And then you use that to stream 5 to 6G movies. Lets further assume that when streaming movies, 80% of the bandwidth use is download use and 20% is upload use so you get 152G of straight download. That would net you 25 to 31 movies a month. About a movie a day. Which I suspect is more movie watching then 90% of the population. Most people will still watch TV shows, spend time with the family not on the computer watching streaming movies, going out with friends, just living life. I think 250G is most likely out of reach for 99.99% of the users of these forums.