Garmin’s backing into the cellphone business in a big way. They’ve already got the GPS navigation thing down pat, so why not add voice, websurfing, MP3 playback, a camera, and a touchscreen to their devices, and save customers from lugging two, three or four items around instead of one?  Meet the Nuvifone.The Nuvifone includes two features relatively new to Garmin navigation — a “where am I” button that tells the user the nearest address, intersection and nearby emergency facilities, and another that can