Foursquare on Nokia N8 (symbian^3) Nexus one (android 2.2.1) iPhone (iOS 4.2 beta) Noia 5800 (symbian^1)
all running side by side on teh same wifi lan. - note though the iOS version crashes - the iPhone is running beta firmware, the N8 is also running pre-release firmware. Nexus one / 5800 have the latest OTA updates.
all have slightly different interfaces but support the same feature set.
iOS/android versions appear to be a little quicker than the Nokia versions. I believe the nokia one is a web runtime app (ie embedded browser app) vs the android/iOS versions being native code.