Since the launch of the New Xbox Experience last November some Xbox 360 users have been having trouble with audio for their systems, trouble meaning audio won't work with HDMI connections. Microsoft had been working on the bug and now has announced that a dashboard update will fix the issue coming early tomorrow morning.
From Major Nelson:
"Starting Tuesday morning at 0200 Pacific when you sign into Xbox Live you’ll be prompted for a mandatory dashboard update. The update addresses the issue that a few folks were having with audio and their HDMI connection.
This update will be rolled out to all Xbox LIVE members around the world over the space of a few hours, so you may not get prompted for the update immediately. Thanks for your patience."
Good to see the issue is finally getting taken care of.