Foursquare has broken the trend and instead of releasing an iPad app went straight to releasing a native tablet app for Android devices. The new update features a new map browsing experience for tablets and larger screened phones, also there are improvements to the Explore feature. This is nice for the Android users of the world where as the iPad users have had to deal with a stretched iPhone version of the app.
Rumours are that the iPad version of the app isn’t far off from being released and the look and feel of the app will be exactly the same as the Android version, so iPad users will just have to used that stretched out iPhone version for check-ins for a little longer. The location check-in app has had a native app for the Sony Tablet S for a while but it wasn’t built buy Foursquare themselves, it was engineered by a third party and not fully featured.
It is important for services to hit the expanded market via the tablet devices and optimizing your app for tablets is definitely a start, especially since location check in is becoming more popular since Facebook added the option to check in to a location.