Almost certainly. I would also expect contamination (finger oils, for example) to be a big issue.

(Source: I worked on and designed equipment for commercial scale-up of a nanoscale superhydrophobic coating process)

I just love that this website happens to have someone in this field to help us all understand this. Thank you for your comment!

Would not water (or any other solvent's) movement cause a scouring action that would remove contaminates and keep the surface clean?

Depends on the behavior with oils I guess.

Water doesn't dissolve oil, although it could help mechanically remove it -- but if the material is actually olephilic or neutral it could be an issue.

I was wondering what would happen if you turned on a firehose and just slammed it for a good length of time...how durable it would be? If they're planning to use it on the surface of an airplane wing -- curious how durable the surface is.

I was actually thinking about using this on the surface of titanium on a catamaran.

I've been wondering the same thing... Besides, there are other differences between lab environment and the "real world" - actual water is full of impurities (e.g. limescale, urea in pee, mud, salt, acid rain, ...), I wonder if the material retains its hydrophobic properties. The other thing that worries me probably even more than "wear-and-tear" (i.e. scratches, abrasion, ...) is dust - once dust covers the fine nano-structure, water will once again stick to it, and it might well be impossible to clean!

Dust, at least, is not an issue like you suspect. The researchers who developed this technique took the dust from a vacuum cleaner and dumped it on a treated piece of metal; water picks up the dust and then slides right off, so the surface is actually incredibly easy to clean.

Sure, but if you dump something on it which has a grain size that's similar to the voids in the material, all bets are off. If the average void is 1um and you put 0.1um dust all over it, I would suspect that it would embed itself in there pretty nicely.

Or a liquid that's not repelled by the surface. What would happen if you just dumped a lot of washing up liquid on this nanosurface? How would you rinse it off?

Watching the video I thought the thing with the teflon was a bit silly. After all if you wanted to think of something that won't hold water at an angle, wouldn't you think of ordinary glass rather than teflon?

Glass windows regularly hold water at a 90˚ angle and against interstate-speed winds.