All phones with Operating system Android v2.1 with TouchWiz UI 3.0. Upgradeable to v2.2 in some countries. Unofficially compatible with Android 2.3 with a port of CyanogenMod.
If you are looking to upgrade your phone because it is boring or doesn't have all of the features you would like, consider these five things to look for when buying a new cell phone to help you decide which phone is best for you.