I just tried this (updated to 1.5) and still get absolutely no sounds. I can play Pandora radio, but when I run Minecraft, I get no sound after completely removing my ~/Library/Application Support/minecraft folder (not just the resources folder, but the whole minecraft configuration folder. Not only do I not get in-game sounds (picking up, attacking cows, etcetera) but I also get no interface sounds anymore (like clicking buttons to start single player or multiplayer.
The resources folder is completely empty, so I tried downloading a resources file form the internets, but I still get no sound..
This is affecting me, Mac OS 2.0.1004 (1367).
This seems to affect me only when my internet connection changes, or when I've been away from the game for a while.