Very tricky puzzle... can you guys solve it?
White to play and WIN!
There was no need for 3. Kxh2. He loses nevertheless.
3. Kxh2 is a blunder, since black would reply 3... Bf4+ and then play 4... Bb8. Apart from that Azkadaz did a nice job by showing all these variations. On the third move white should leave his king on h1 and play 3. a7 and get a queen next move.

Gah! It annoys me when people only post the finish of a beautiful study instead of posting the setup as well. It's like posting Rd8# without the rest of the game for Morphy's Opera game... a study is a work of art and you don't do it justice if you deliberately leave it incomplete. For anyone who cares, the study in question was composed by Reti in 1922 - here is the full study.
Hint: Zugzwang.