I've upgraded to ubuntu 11.04 and since then the audio stopped working (I was on 10.10 before that).
I'm using a Macbook Air 3,2 and these are details of my audio card:
description: Audio device product: MCP89 High Definition Audio vendor: nVidia Corporation physical id: 8 bus info: pci@0000:00:08.0 version: a2 width: 32 bits clock: 66MHz capabilities: pm msi ht bus_master cap_list configuration: driver=HDA Intel latency=0 maxlatency=5 mingnt=2
It doesn't work either with headphones or speakers.
Alsa mixer doesn't show anything muted and all the volumes are up.