Subject: holographic data storage

In the late '80's, I came up with an idea for storing data in a three-
dimensional matrix (i.e., in a crystal).  Years later, I read that 
several companies are actually making progress on prototypes of this 
(and including ideas I hadn't thought of; i.e., not only are three 
dimensions allowed, but data can be 'stacked' on a single physical 
point merely by changing the angle of view of the reading laser.

My question is, what further progress has been made on this?  Are 
there any projections as to when such devices will become marketable? 
What kind of capacity can we expect for the early models? (i.e., is 
this in the gigabyte range? terabyte?)

Re: holographic data storage