According to this Twitter blog entry satellite phone providers can now receive sms Twitter messages that post direct to a users Twitter account. If you are in a country outside of America where the free access to cellular or internet networks is limited or dangerous this is a great new service. It is not a bulletproof way of getting your position out onto the internet. (Not any more) So one needs to be careful about which satellite provider one uses. There are a wide range of phones to choose from and you can find a lot of them here.
All of them can charge a cell phone or satellite phone and have 4 different power sources. So with a sat phone and the voicelink one has a way to communicate locally and globally completely off the grid. Not bad for well under 1,000 dollars and almost no technical knowledge needed. I imagine this would be useful in places like Homs, Syria about now.