No rules against it, but it's not something that a lot of runners find necessary.
Some use a waist pack (smaller, closer to the body) that can range from a fanny pack style to hold ID, keys, some gels, ipod, and a drink bottle (or small bottles around the waistband).
Some may have a camelback style backpack.
Me...I don't want to be encumbered when I run. My solutions for those things you are carrying:
iPod: I don't tend to race with one, because in triathlon, you can't, and I don't want to get dependent on it (so many are!). Besides... there is more than enough entertainment at the Disney races. But I can see that people love theirs. (see another iPod statement below since you're a newbie to this)
Sports drink: For Disney (and really most any race), there is more than enough water and sports drink along the way. I don't carry fluids with me at any running road race, from a 5K up to a marathon.
Snacks: I do need a place to carry gels or shot blocks...I try to use what is on the course, or I have some small pockets in my running clothes. Or if it is cold, I tuck gels in my running gloves.
Extra clothes: the Disney races have drop bags that you can leave at the start and pick up your extra clothes at the end. If it's going to be cold (esp a la 2010!!), I wear extra clothes that I am going to toss on the side of the road (get them at Goodwill or
Walmart on sale...all clothes picked up go to charity). I personally would rather not end up with half my wardrobe tied around my waist or in a backpack.
Note on Ipods since you are new to running, esp a huge event like Disney. Keep the volume very low, or run with only one earbud in. There are some very congested areas, esp in the first several miles, and definitely in the parks. Runners will need to be able to communicate to each other to pass and hopefully will try to give you a heads up (rather than an elbow in the side) if they need to pass. If you can't hear them because you are zoning out to your tunes, you might get the elbow in the side.
Also, I won't cheer for you if you can't hear me. I hate telling runners "good job" etc and they can't hear me. It's part of the fun to interact with the other racers, so don't totally get in a cocoon of your own music!
