Is it a good idea? Listening to your iPod while out for a jog? Two incidents in the last week bear mention. First, the female runner who apparently was killed by wolves while out for a run in Chignik, a remote part of Alaska. Second, the beach jogger who was killed by a plane making an emergency landing in Hilton Head Island, South Carolina. In both cases, they were apparently listening to an iPod.
Now, it's hard to make a definitive statement that without the iPod, they might still be alive. The runner in Alaska was 4'11" and probably weighed less than a single wolf, much less a pack. Regardless of whether she was running with an iPod or not, if they had attacked, she probably would have stood no chance. In the beach case, apparently the plane had cut its engine and was gliding. Combined with the sound of the waves and wind, one can see how it's possible to not hear it come. Again, it's not clear how much of a difference the iPod would have made. On the other hand, it's possible that someone else saw the plane coming down and started yelling but the jogger didn't hear it because of his iPod. You can never know for sure unless you were there yourself.
Personally I never listen to music while out for a run. Safety being the first factor, but also because I don't like having things in my ears. Even if I did, I don't think I would do it while out on the streets. Maybe on trails.
Music might be helpful and in some cases, maybe even essential, for some people to go out and run. However, one should be aware of the fact that he/she is taking a risk while doing so. How much of a risk? It depends on the person and the environment. Some people have a tendency to get lost in music so much so that they lose track of what else is happening out there. That definitely puts them at a disadvantage when it comes to dealing with any unexpected turn of events.
The environment makes a big difference too. For example, city streets are definitely not the place to run while listening to music. Some people might argue that city streets are not the place to run. Period. Even out on trails, one needs to exercise caution and weigh the risk factors. A couple of years ago, I was in Katmai, Alaska which is another remote part of the country and a great place to see grizzly bears. Even though it was beautiful and very tempting to go for a run, I chose not to mainly because I didn't want to go alone. On the other hand, I've gone running in Yosemite out in the wilderness by myself. These were on plains where I could see the terrain far into the distance and it was in the middle of clear and sunny day.
In the end, it is a choice you make for yourself. Just be aware of your choices and the associated risks. Happy running and stay safe.