Check this out as a warning against long use of a laptop on your lap. It's from Yahoo news. I doubt that an iPad gets to 125°F when used on your lap.
http://news.yahoo.com/s/ap/20101004/ap_on_he_me/us_med_laptop_toasted_skin
http://news.yahoo.com/s/ap/20101004/ap_on_he_me/us_med_laptop_toasted_skin