Comment 3 for bug 888136

I've got similar problems. Sometimes sound output via the headphone jack does work, but not always.
Aside of this, sometimes (apparently mostly after waking up from suspend), sound does not work for some applications (like vlc) but does work for KDE desktop soundeffects.

Additionally to the problems introduced by the Oneiric release, my (internal) microphone doesn't work at all (since like 8.04) without a patched kernel (found here: https://launchpad.net/~c4pp4/+archive/ppa).
Less importantly, but irritating none the less: when the power cable is unplugged, a chirping noise is heard through the built-in speakers. It's not present on the headphone jack (if it works).

It would be marvelous to have this working out of the box in mainstream. I'd be happy to collaborate on this topic, just contact me.