We get the ordinary social media. People can engage on-line with friends, colleagues - even strangers with a common interest. And it not just fun - it's a really useful tool to mobilise people whether that's for a spontaneous party in Time Square or a political rally in Tunisia. We get celebrity twitter too. It is so easy to communicate to eager fans and keep them engaged whether that's with serious commentary on the current affairs or simply feeding them celebrity tittle tattle. But what about corporate twitter? Is it really that important to corporates and if it is - what should businesses be doing about it?