I got this through on an email the other day from Riegl. This is meant to sort out the problem of very shallow water but seemed quite far off being a product last year at ELMF. It looks like they have been working hard.
RIEGL VQ-820-G – Airborne Laser Scanner for Bathymetric Use
The VQ-820-G Bathymetric Airborne Laser Scanner with echo digitization and online waveform processing provides high speed, non-contact data acquisition utilizing a fast line scanning mechanism and a powerful laser source, emitting visible green laser light. For this particular wavelength, the instrument can measure the bottom of shallow waters due to low signal absorption in water. The VQ-820-G is designed to survey the coastline, the water surface, and the seabed or ground of a river or lake, depending on water turbidity.