Use a satphone. With a bit of moving around you can usually get a signal from inside the aircraft. For a more robust solution you can mount an external antenna. You can then use this for sending periodic text updates, or generating a dialup connection and pulling down basic METARs, queued emails, NOTAMs, etc. Apparently the GPRS functionality is not usable.
here is a link to a comprehensive discription of a light aircraft approach.