Pinspiration is as close as Windows Phone users are getting for now to an official Pinterest app, which is currently an exclusive for iOS. Regardless of whether or not you have a Pinterest account, you can use Pinspiration to browse and share pins, and the most popular pins currently being shared will rotate on your Live Tile.
Pinspiration in theory allows you to log in to your account, but many users have reported problems with this, likely because Pinterest put down the clamps on non-official Pinterest apps being able to log in to the service. If by some chance you are able to log in with Pinspiration, you can check on Pinners You Follow, as well as pin and repin photos.
A free version and a paid version are both available. The free version is ad supported and limits the number of times you can check Pinners You Follow. The paid version removes both. Pinspiration Pro costs $1.29 on the Windows Phone Marketplace.