Well, you may have a point about winter as I live up north in a colder environment. The air is dry in the winter allowing for charges to build and not dishcarge so easily but for us\electronics, this is not good. When there is a better amount of humidity, this aids in discharging those little electron buggers before we do. So cold, dry air will definately aid in a zap. We just bought my son an ipod this X-mas, and so far no zapping and he has worked out, etc...with them on but I will ask him regularly. I would think the headphones should NOT be a discharge agent unless very poorly made. I have had the old cassette, cd player, now MP3 players, with headphones, no zap. I have worked with many electronics and in my opinion, the ipod has an issue with not the headphones specifically, but grounding in general. I don't think we are shocking the headphones, this is a two way street here but poor equipment makes it more likely. The headphones are grounding the person to the ipod, or vice versa, causing this shock which means the ipod probably has it's own issues with static and is dishcarged through the easiest means as electricity takes the easiest path. The headphones are grounded to the ipod so in my opinion once again, it comes from the source, not the headphones. The touch pad may have something to do with this as you mentioned about grounding yourself out every so often. Either way, I think it's the ipod.

Paul