http://egami.blog.so-net.ne.jp/2011-09-21
(Google English Translation Here)
It is described that the OIS glass element is retracted when the lens is not used. The element is moved up and down along guide rails and there is no sound generated. Here is the side view of the retracted lens:-
But however, I have a very hard time to understand what is the benefit of this design? It is mentioned somewhere that the lens could be made thinner, but is it really true? In contrast, without any doubt, with the additional mechanism that is included for such a complicated design, the lens diameter and size will be increased and centering accuracy could be affected, optically, which is of prime importance as IQ will be affected in the end.