I've had an iPad 2 since its release. I've never felt it get hot, and I live in a climate where 100 degree weather is common.
My iPhone 4S gets toasty when charging or talking on it for long periods, but nothing odd or even remotely bothersome.
I can see this in a MacBook Air, though. More specifically, an ARM-based MacBook Air that needs a light breeze to cool down, not a ferocious wind like Intel's x86 chips.