Twitter, presumably in a bid to become all encompassing, has signed up for use of two satellites that let you tweet even when you have no mobile signal.

Using a special code you will be able to Tweet (like sending an SMS) from your mobile even when there is no connection from your network. Use of the Iridium and Thuraya satellites is ideal for news journalists, the public suffering under mobile network controlling dictators, and those without smart phones. Sure you’ll probably never need to use it (unless you get kidnapped in a war) but it’s just nice to know its there.