Fantastic invention, I would definately buy clothing with this stuff on it as its allways bloody raining in the UK. Can you imagine the practical joke possibilities with this stuff, give your friend a toilet roll coated in this stuff for example
I bet it's nonbreathable though so it might not be the best choice for many applications (like shoes which you sweat in).
Clothing wouldn't be a good idea. Now rain suits and umbrellas would be good. And on cars. Even on roof tops. There is a lot of things this would be good for.