Mass Storage availability may vary with device and ROM, but ROMs such as CyanogenMod and a few others running on JB 4.1.x are detected by Windows as a portable device, not a USB Mass Storage device. (CM doesn't attach the phone as a Mass Storage device, regardless of the OS version of Android it's running. AOKP, SlimBean, and ParanoidAndroid attach the device as a Mass Storage device however.) Samsung handsets use Mass Storage on stock TouchWiz, to Google's dismay. (Big Sammy STILL refuses to put on-screen navbar buttons on their smartphones)
I'll never get the deal with OEM's trying to differentiate their phones significantly, resulting in the pollution of Android's overall experience.
Posted via Android Central App