Ah-hah! There we go. Just days ago we were pointing out how strange it was that Foursquare still didn't have a proper Windows Phone 7 application (especially as Microsoft had touted Foursquare around as a partner since the very beginning), and now they've gone and made things right.
Following Gowalla into the Windows Phone fray by less than a week, Foursquare has just pushed their official WP7 application into Microsoft's Marketplace. It looks like that extra time in the oven really did it some good. It is, perhaps, the best looking WP7 application we've seen on the platform to date.
If you've got Zune installed or you're on a WP7 handset, you can find Foursquare for WP7 right here. If you're neither of those things, you'll just have to poke your finger at the screenshot up above and pretend.