Keep it out of the sun and it should help. In the sun, it might get up to 80 degrees F (mine did), and on warmer days during summer, it may go even higher.
I got mine at Best Buy on Wednesday 10/AUG/2011 for $170 (through a price match on Friday of the same week), and am still eligible for the ambassador program!
Now that you modified the 3DSWare's header, would it be possible to do a bannerbomb exploit for the 3DS? I'm buying one next week when they drop the price, so I may be able to help test it.