a couple good points in here.

people tend to do slower, longer cardio. THey fail to see results and wonder why.

The key is intensity. 100% intensity...as hard as you can possibly go for shorter durations is far better than anything else. In fact, 1 100m sprint per day is probably better than a moderate 2mile jog.

These go by a couple names... Tabata intervals and Phil Campbell calls them Sprint 8's. Check them out. Both advocate "sprinting" (100m dash, 10second sprint on a bike, etc) as opposed to long, moderate exercise. sprinting is defined as anything that requires 100% exertion (for about 10seconds) that leaves you breathless, bent over gasping for air.