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In short, yes. It tough to be able to use your laptop actually on your lap but being so thin and so fast and being made from aluminum, they definitely get quite warm. It's because the aluminum dissipates heat so quickly that it actually gets so hot. To a point, the hotter it is the faster it's cooling.
 
Download iStat Pro and read the temperatures. We all have a different definition of "hot" so use a scale we can all understand.
 
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