It's due to the older chipset that's in these things. We have what's called 2.0 chipset. 2.5 is supposed to be smaller and cooler. It will be released this fall.
So I guess theres like a CPU, or the equivalent of, thats generating all this heat? I sure hope the ventilation the unit has is adequate. Seems like this much heat in something so small would seriously shorten its lifespan.
As long as you keep air circulating around it you will be fine. During my drives to work I keep the A/C on anyway and it is only lukewarm to the touch. At night on my way home I usually just have the vent on since it's only upper 60's to mid 70's outside and it's the same way.