Bad heatsink (MBA):

Good heatsink (MBP):

Don't ya think Apple could squeeze a fin or two onto the MBA heatsink somewhere? No wonder it heats up so.
I think the case IS the only real heatsink on the thing. Once the case heats up a bit, on go the fans.
At least the MBP has some fins so a little bit of airflow seems to dissipate a lot more heat.

Good heatsink (MBP):

Don't ya think Apple could squeeze a fin or two onto the MBA heatsink somewhere? No wonder it heats up so.
I think the case IS the only real heatsink on the thing. Once the case heats up a bit, on go the fans.
At least the MBP has some fins so a little bit of airflow seems to dissipate a lot more heat.