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My new Mini Displayport to HDMI from Monoprice.com outputs both video and audio to my TV. You have to select HDMI under Output under Sounds in System Prefs.
My Monoprice Thunderbolt to HDMI Adapter - Product ID 5311, works just fine on my new 2011 MBA, as well as on my 2011 MBP including sound transfer. NO problem with sound transfer to my TV. Works like charm.
 
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