For Windows Phone, until now "Wimosquare" was the only option for a dedicated Foursquare mobile application. Now, there's a new Foursquare client in development, dubbed "MySquare" which looks to have it all: check-ins, tips, friend lists, the ability to explore points and badges, GPS access, and more. It'll be available in two versions: a free, ad-supported client and a premium, ad-free version with full map services integration.
MySquare will work on Windows Phone version 6.0 and higher and requires a touch display. MySquare is still in alpha, if you want to be notified when it launches, sign up.