I ran into my first annoying bug in Snow Leopard today. Not a big deal, just annoying.
On reboot, I noticed that the volume was reset to 100%. First I thought I forgot to set the volume to a lower level, or I increased it and forgot to pull it down again.
But after rebooting twice on a short timespan, I was sure I decreased the sound level before reboot but it was still reset to 100%.
A quick Googling learned that there are two audio settings files in /Library/Preferences/Audio (com.apple.audio.SystemSettings.plist and com.apple.audio.DeviceSettings.plist) that should be removed. On that forum, there are comments of Snow Leopard users that say their sound settings are reset to 0% or 25% so I guess the volume level is restored to the level at which it was before upgrading to Snow Leopard. But that’s just my guess.
Reboot and the volume stays at the same level as before the reboot.