The cisco literature references 12 inches as the acceptable distance between you and the AP or client device. There are several opinions here. Jack's is pretty much the only one with a whole lot of validity. These are extremely low powered devices however they are emitting microwaves at that low power. Years of use and/or study of the 802.11 environment is the only real way to know for sure if they are causing any damage. If you wore two AP's like earmuffs then I would say it's a pretty good bet you'd have lumps as ears at some point. As far as just having your AP on your desk or your PC card in your laptop and what effect that will have on you long term, it's just conjecture. IMO, it's not a problem, but I can't say that without the disclaimer that it is merely an educated opinion. As with cellphones, tests and time will tell.