Shipping corals and/or fish for 24 hours.

[bluetang]

Shouldn't be a problem, You need to remember these fish and corals come from around the world and sit on runways and in warehouses for a few days before they get to the LFS.
IF it is cold get one of those hotshot hand warmers and stick it in the cooler or the box it is shipped in. Just make sure you tape it to the top of the box and that it doesnt lay directly on a bag of water and warm it up too much.