Actually there is an ALSA device (libaudio to be more specific) mapped as arecord (and aplay) will work, but it seems that nothing else can use the DSP, and you have to ask it nicely (a DSP supported format, rate, etc.) which gstreamer does...
cvlc v4l2:///dev/video0:chroma="UYVY":width=320:height=240:adev=default:audio-method=2:samplerate=8000