I just updated my OS and noticed that I have the ability to use the Mobile Wi-Fi hotspot and the tething mobile broadband features on my Droid X now. I have not signed up for the $20/month service to use these features. When using the mobile hotspot/tething, will this be free then? Or will I be charged as I use it? I don't see any information on VZW's web site indicating a per kb or mb charge for hotspot/tethering usage.