i've read several articles stating that hitting the bag without boxing gloves and/or tape will result in calcified joints and athritis, can anyone support or refute this?
also, for the guys that do conditioning, what part of the hands do you condition? is there any chance that you will develop athritis later in life because of your conditioning?

I'm to young to answer this question, but I never wear gloves.

Mozart, my own experience indicates that if you start out very light and build up very slow, yoiu will be ok, but if you push it to anywhere close to feeling pain (remember, some pain comes long after repeated practice and may not be directly attributable to the practice at first) you will find a great setback in your training. Patience really is a virtue here. Those guys with calluses, deformed fingers, etc. is probably not the way to go. Might I make a recommendation of no more than 30-40 strikes per fist on your bag or pad, no more than 3 times a week followed by massage and bruise medicine to start out with. This is one kind of workout that you should never feel like you had really pushed yourself.

if you learn how to punch properly AND engage in training that requires multiple rounds on the heavy bag you should definitely wrap your hands and wear at least 12 oz gloves. there are a number of good resources on the web to learn how to properly wrap your hands. i don't like canvas wraps...i prefer the mexican-style wraps that are like bandages. use two per hand and throw them away after four or five sessions. people who do not wrap their hands rarely engage in boxing type workouts on the bag. said workouts will damage your hands. even with wraps and gloves you will find your hands still sustain damage.