[Matt]

It really depends on what you want to get out of it. Jogging for an hour or so can be pretty pointless, particularly if you aren't trying to lose weight or want it to benefit your golf. If you want to add power, interval training is where it's at. Sprint for 1 minute, walk for 30 seconds, work up to 20 minutes of this kind of work. Mark Verstegen has good information on cardiovascular training for athletes in Core Performance.

Matt

Interval training is an excellent, efficient option. You can attain results in 15 mins instead of maybe 45 mins of steady-state cardio. I personally hate running so if I do run for cardio work then it's intervals.

In my opinion, steady-state, long duration cardio is really only beneficial to those training for such a run (marathoners, etc). Otherwise, long runs can really wear your body down. Plus it's just plain boring. I think 20 mins is a good duration for a "normal" running session, but do more if you're not concerned about sacrificing muscle. And don't forget to always be progressing - works very much the same for cardio as it does for weight training.