IGN's taken the Nyko PS3 Intercooler out for a spin on their PS3s and came to one conclusion: It's loud. The cooler itself attaches to both the back and the side of your PS3 and has a knob to adjust fan speed depending on if you're doing some heavy duty processing (like Folding@Home).
However, beyond stating that it makes the PS3 noticeably louder and that it moves "dramatically more air" through the PS3, there's not much information. What's the temperature reading before and after you add this on? While playing a movie? While using Folding @ Home? While gaming? We'll try and get a hands on and see for ourselves.