I noticed that my PuTTY session to my MacBook (which is now on Mavericks 10.9.3) seems to stay alive with the clamshell closed so long as the power cable is plugged in to the laptop. This can be seen by unplugging the power, the terminal stops responding after 10 seconds or so, but comes back once I plug power back in, all while the cover is closed.
While this is extremely convenient given how my desk is set up, I can't help but wonder how overheating can be prevented. Obviously some reasonable level of CPU clock and power management would take care of it, but I would only be extremely impressed and remain incredulous that this is something that has been achieved.
So, what's going on here? Is this the "Power Nap" feature at work? If I start running some CPU loading benchmark from the command line now, what will happen?
I tested just now by running
yes > /dev/null & yes > /dev/null & yes > /dev/null & yes > /dev/null &, and it sure did get the fans spinning, I open it up and it was definitely pretty toasty, so that would not have been good if I had the machine out of physical reach.