Believe it or not there's only a MONO speaker in the MacBook Air as it says on the Apple website.
Guess there wasn't space for two ...
Maybe it'll be like the iPod "speaker". You'll hear beeps, and nothing else.
but there is stereo out for the headphones isn't there?
From one of the early previews it states the "1/8" Audio Output" is mono as well. That could just be a guess. I do hope so.
Macbook air tech specs :
what does omnidirectional microphone mean?
Just means it can pick up sounds from multiple places. You don't have to be talking directly into it.