At least on OpenSuSE 11.4 x86_64 if you copy the pulse audio plugin from SqueakVM 4.4.7.2357-linux_i386, and the evaluate AbstractSoundSystem soundEnabled: true. The sound works.
To see if sound works on Linux, I grabbed Squeak 4.2 - it works, at least on Ubuntu Lucid. �In Pharo 1.3, I can't enable the sound preference. �I'm not sure if that's good or bad :) �Any ideas?