Comment 3 for bug 992644

I can confirm it working under oneiric. Under precise, in alsamixer you can notice following:

With headphones disconnected Speaker level is automatically set to 100:
http://i.imgur.com/rFuPX.jpg

When connecting headphones Speaker level is automatically set to 0 and muted. Headphone volume control is unavailable:
http://i.imgur.com/npDXy.jpg

Increasing volume of Speaker (while muted) increases volume in connected headphones (laptop speakers remain muted):
http://i.imgur.com/uBIDT.jpg