The key is that it doesn't run hot. All that hot air is blown out quietly and effectively by the great cooling system in there.
The key word there is quietly. My cousin got his 360 back from being repaired and noticed that the fan was even louder than before. Maybe they upped the fan speed to help keep it cool, not sure.
Anyway, congratulations Tempest. I hope you enjoy your new PS3. If you decide to run folding@home while your PS3 is idle we would love to have you (and anyone else who is interested) in our Atari Force group. While f@h is running, just hold down the square button to see the controls. You can change your donor name and join a team under the Identity option. Our team # is 56067. I've been runnning my PS3 for 3 weeks straight, 24 hours a day. When I'm not playing Oblivion, demos or watching videos it's been folding. I did reset it 2 times, so we'll see how it does in a few more weeks of running constantly.