Ted posted a great piece on suburban sprawl in Calgary, with references to the Sierra Club's research. I agree that Calgarians are afflicted with the "Don't fence me in" syndrome. A city with the geographical area of Orange County, but a population of only 1 million people. Calgary has approximately 10% the population density of New York City. About 20% the density of San Francisco. About a quarter the density of Vancouver. (comparison of various population densities)
Calgary has approximately the same population density as Boise, Idaho. That just doesn't scale. Nobody wants to turn Calgary into New York City - that density would drive most Canadians insane - but approaching Vancouver's density wouldn't necessarily be a bad thing, if done properly.
As a SUV-driving suburban dweller, I'm as much a part of the problem as anyone. My footprint is much smaller than many others, though (my SUV is really just a big station wagon, built on the Camry chassis rather than a Big Heavy Truck frame, and my suburban home is a decidedly modest one, with 1,400 square feet and a lot that is only ~36 feet wide).
But, the design of my suburban community could be much better. The commercial services are all aggregated in the exact centre of the community, meaning those living toward the edges are much more likely to drive to the corner store (it's a 15 minute walk from my house - one we don't take often enough).
One thing in our favour is the public transportation system. Although it's far from perfect, I do get almost door-to-door service between my house and the University via bus. And the LRT is coming closer, meaning the schlubs that have to commute downtown will have an easier time leaving their H2s at home.
Update: The comparison between Calgary and Orange County was unbelievably inaccurate. Calgary is much smaller than Orange County, and actually has a higher population density, according to Wikipedia.