Not sure if this is an isolated set of circumstances relating to the arrival of summer here in New Zealand or a genuine concern for the new MacBook Pro range, but each model that I have tried has been noticeably hotter than the older MBP.
I assume this is at least in part due to the tighter packing of components and a smaller fan, but after a couple of hours use the area of, and around the keyboard becomes noticeably warm to the touch. By lunchtime that's become more than warm and I would say is actually hot.
The same is emphatically not true of the older MBP (nor either of the MBA models I have access to).
Is this a result of Apple's 'slim is the most important feature of each and every thing we do' strategy? If it's something that others are reporting to it would be hard to avoid such a conclusion.