The site is actually a bit of a joke, set up by Primary Coffee Company to turn apples into applesauce after reports that Apple's newest generation of iPads have a problematic overheating problem. If you do take HotPad seriously, rest assured that the site will not "break, melt or otherwise destroy your iPad." Unless, of course, you spill the coffee on it, in which case the liability is all yours.
Meanwhile, Apple insists that iPads run "well within our thermal specifications." And a Wired investigation into the heat issue pushed the iPad to 108 degrees Fahrenheit after 45 minutes of intense gaming. While the iPad wasn't as hot as their cup of coffee (121 degres Fahrenheit), it probably was just enough to keep the mug warm.