The Maemo 5 Developer Guide in the section Imaging and Sharing shows that the camera control is handled by GDigicam and Camerabin (both rather high-level).
danielwilms posted links to GDigicam and Camerabin examples here. Camerabin is contained in gst-plugins-bad.
Check the photography interface for the information that is available internally.
I think this interface is actually implemented by gstv4l2cam (gstreamer0.10-plugins-camera). I am not aware of documentation for this outside of what you get via apt-get source.