SpringHeeledJack is right. The MobileMe find service only works for iOS devices. When everyone is migrated to iCloud, then I believe Mac OS X Lion will have a similar function for Macs. I doubt it will have the capabilities of Hidden though. The current service simply gives a location and allows you to send message to the iOS device, sound the ringer, lock it or wipe it remotely. I would expect the Mac OS X version to be the same, and not have the picture taking ad activity recording features.
Better than nothing though.