McMaster press release ("No time to get fit? Think again"):

http://dailynews.mcmaster.ca/article/no-time-to-get-fit-thin...

Study ("Twelve Weeks of Sprint Interval Training Improves Indices of Cardiometabolic Health Similar to Traditional Endurance Training despite a Five-Fold Lower Exercise Volume and Time Commitment"):

http://journals.plos.org/plosone/article?id=10.1371/journal....

To be clear, three 20 second all-out intervals interspersed within 9 minutes total of warm-up, cool-down, and easy intervals.

One minute? Try an all-out set of 5 reps on the deadlift, killer full-body workout in ~12-14 seconds.

That being said, though time is the most frequent excuse people make for not being fit, the reality is that most people are really bad at making themselves do things that are uncomfortable, so it really doesn't matter how long a workout takes.