State of the art of waterproofing
The best existing solution is something that is called parylene, if you can put a film of this down without pin holes then you can have a water barrier and dielectric barrier.  Often used in space and extreme environments.  I've seen a 20KV voltage source that looked like a bare board that you can hold in your hand.

Parylene is relatively expensive, partly because of raw material cost, partly because of application technique.  It is applied as an evaporative coating, which can be very wasteful as it coats the inside of the chamber so only a small percentage ends up on the board.

Whether of not this Liquipel can be used in electronics will have to be tested.  What is important is that you form a physical barrier that bonds to the surface. The material that I saw demonstations of in the past (80% that it is this Liquipel) used a nano-layer to entrain/entrap air as a buffering layer.  This material will wear off eventually and counts on a rough surface (nanoscopically) to entrap air which then form the "barrier".  So it is using van der waals forces and not covalent bonds.  These bonds could be saturated with other materials after mechanical abrasion/contact.  Also at corners, say the edges of leads on a IC package I could see that this would be a place where this material might fail as a nanoscale structure might not conform around a corner fully.

But these are areas to look at, not necessarily a reason to reject it until proven not to work.