one of these some time ago, curious to see how well it would work. Answer: it works very well indeed! The claim is that it works via “gecko-like nano-suction”, allowing one to stick things together that wouldn't ordinarily do so – and then to be able to pull them apart again. What the photo shows is entirely realistic – despite finished wood not being a perfectly smooth surface, the nano-pad sticks to it quite nicely.
So that got me curious, of course. Just what is this “gecko-like nano-suction”, anyway? I envisioned a perfect array of thousands upon thousands of little tiny suction cups, but that's not how it works at all. Instead, the surface is pocked by thousands of randomly shaped and placed little microscopic pockets, as you can see below. The silver arc is the edge of a dime, to give you some scale. The photo is at 60x magnification. You can see dozens of oddly shaped little squiggles here; those are the little pockets that act like suction cups. Some of them, if you look closely, are filled with dirt – which will wash right out, making it good as new.
I had a heck of a time getting that dime off there when I finished taking this photo :)