PinStrap is a responsive WordPress theme that I give away for free over at BragThemes. I built it while playing around with a relatively new jQuery plugin called Woomark. The theme also uses ajax to load new items as you scroll down the homepage like Pinterest.
PinStrap also includes the Twitter Bootstrap framework so you can use all the CSS and jQuery goodies. Since we launched the theme, people have been downloading it like crazy! The first day is was downloaded around 200+ times.
If you want to run your own little Pinterest style website, Pinstrap is a great solution.