They used to ice the intake (besides just cooling the engine overall) in an attempt to get as cool of a charge as possible. The theory was good, but I'm not sure if it made much difference since the A-F mix went through the ports so fast. Also, when the fuel mix comes out of the bottom of the carb it cools things anyway. If you ever run a tunnel-ram you can watch the outside of the top piece of the intake actually start to ice up after running for awhile.
X2 on that. There is a tremendous cooling effect due to the pressure drop through the carburetor venturis. It's there on a standard manifold, just much easier to see on a tunnel ram.