[ryude]

It cools down the intake charge from the turbocharger going towards the throttle body/intake manifold.

 

[ryude]

SX2.4 is correct, the heat comes from the exhaust which spins the turbo. If you don't run a intercooler you get hot boost. Its not efficient, but also raises cylinder temps/engine temps considerably. The intercooler cools the boost to eliminate this. This is not the case for superchargers because they are engine driven, thus no intercooler.

Superchargers are intercooled as well, just not all of them. Not all turbochargers are intercooled either, although there is little to be gained without one.