The Dutch website ran a GLBenchmark test on the new iPad and the iPad 2 and compared the infrared profiles of each device. According to their measurements, the hottest part of the new iPad reached 33.6 degrees Celsius (92.5 degrees Fahrenheit), while the iPad 2 ran at a cooler 23.8 degrees Celsius (74.8 degrees Fahrenheit). You can see the differences in the image above where the new iPad is on the left and the iPad 2 on the right.
The team at Tweakers attributed this difference to the quad-core GPU of the new iPad. When its being stressed by a benchmark test, the GPU will generate extra heat that'll raise the temperature of the device. Though high, the levels measured by Tweakers were still within the operating limits of the device which are 32 degrees to 95 degrees Fahrenheit (0 degrees to 35 degrees Celsius).
Even if more reports corroborate these results, this excess heat issue won't be a problem for most people. If you game a lot and live in a warm climate, you might have to watch your usage, but most people don't stress their devices with heavy gaming. Under normal usage, the iPad might get slightly warm, but it shouldn't climb to the point where the device regularly shuts down.