Since a few days there's a new firmware update out for the fan of the macbook. The mayor changes are, that the fan is running all the time at a very low and quiet level and it kicks in faster already at temperatures above 70°C. So you'll hear the fan now more often, but you have a better feeling that the book doesn't overheat and you can really use it as a laptop (placed on your lap while sitting) again. This means that there is nothing to complain about this thing anymore :-)