Wirelessly posted (Mozilla/5.0 (iPhone; CPU iPhone OS 5_0 like Mac OS X) AppleWebKit/534.46 (KHTML, like Gecko) Version/5.1 Mobile/9A334 Safari/7534.48.3)
IIRC, the vibration motor was changed in the 4s from the gsm 4. I believe it was said that the same motor that's currently in the 4s was used in the vzw 4.