I recently needed to work out of my notebook, away from office and home, quite a bit. I would usually wifi-tether from my phone. But extended 3G+Data+WiFi on the phone would surely drain its battery pretty quickly. If there is anything the MacBook Air needs, it is built-in 3G connectivity. Some people have 3G dongle, but I don’t. Besides, a 3G dongle would also need an additional SIM card. Quite surprisingly, the place I was camping out of had good…