I'm not sure where these kiosks are. The pricing I saw was in pounds, so I'm assuming they're only in the UK at the moment, but I assume the company would want to expand if they're successful. At any rate, it's an interesting concept.
Even a confirmed "no nail polish" person such as I am could see doing something like this for a special occasion.
For those who would prefer to try their own designs, here's a link to some cute fingernail design ideas that seem pretty simple.