There are several bug fixes for the sound issues with SMP, the lag and other issues related to sound should e gone now.
So, yes atomic, could you please update it ASAP? It will help with the lag issues and sound getting stuck in the client.
Edit: Looks like he did update, so, get the update everybody. Also, Bong, I hope you don't mind the 2x2 escape stairway that I made to get out of that lava area. I don't know whether that cobblestone blocking the top of the elevator was intentional or not, but I had to remove it to get out, I'll replace it though.
Edit2: Bong, can we have the OD scanner back?