Well, here's a quote from the previously mentioned appnote... http://www.maxim-ic.com/appnotes.cfm/an_pk/1090

Schottky-Diode Termination
Schottky diodes offer an alternative termination when power dissipation is a concern. Unlike other
termination types, Schottky diodes do not attempt to match the line impedance. Instead, they simply
clamp the over- and undershoots caused by reflections.
This image is an example of unclamped overshoots ...
Ignore the yellow line.