Typical of the complaints (via the Apple Discussion Boards):

Just got my new iPad. I'm loving the screen and speed but there's something weird about it. It gets rather warm/hot after 30minutes of usage. It has never happened on my iPad 2. Do you think it's harmless or .... ?

My 64gb, wifi/LTE new ipad is 96.8 degrees currently (and must have crafty artificial intelligence because it's as if it KNEW I'd brought out my laser temperature scanner and cooled down for reading). It has been very hot to hold, lower left side, since first use. I'll continue to monitor with scanner...

Mine is a 64 with WIFi and LTE - LTE not hooked up yet - got hot enogh that I measured with infared thermometer and it was 117 degree after 10 minutes - my little boy says its too hot to hold - (Great !) but seriously its not comfortable and I will be returning to the store

source: http://www.huffingtonpost.com/2012/03/19/ipad-overheating-problems-issues-complaints_n_1362659.html?ref=technology&icid=maing-grid7|main5|dl6|sec1_lnk3%26pLid%3D144673

so, all the doom and gloom "handhelds will kill console" and then shortly after release the ipad can't handle it?

Any newly released console is going to have problems out of the gate. vita, 3ds, 360, PS2, etc etc. None of this it out of the ordinary

That's a problem? You can use it both as a tablet and as a heater for the room it's a ingenious idea, innovation at it's best!

So it really is a toaster, too? Wow. What will Apple think of next?

it's not an issue! It's a Feature!

A lot of them seem to fix themselves if you cycle the battery.