I get asked why a lot. Why should we do a Facebook fan page? Why should we get on twitter?
There are many sites, if you Google these questions, that will give you compelling reasons for doing so. The simple answer really has to be why not?
If people are getting information from these sources, if online journalists are reaching audiences you need to engage with through their blog posts, twitter streams and Facebook information pages, then – if you are in an organisation that can afford to be there too – then why would you not?
The question is, can you afford to be there, as much as it is can you afford not to be there?
Emma Mulqueeny 
Good point. Sometimes I wish I was asked the question that way round: ‘why do we have to be on Facebook’ would make a welcome change to ‘we must be on Facebook’.
More likely, many government teams don’t stop to consider whether they can afford to be on there; posting regular updates, providing compelling content and responding to questions.
there is a counter argument which says that govt is poor at and struggles with IT and is ripped off at every turn by IT providers..so shoul not follow every IT fad going and instead wait till technologies and markets settle before adopting new products. A further counter argument is that govt spends too much time already in vacuous communication and not enough on developing and implementing coherent policies and should be doing less of everything for the simple reason we have a deficit [spending more than is raised in taxes] and must address that. Facebook may be a good tool; so may Twitter; so may other communication tools such as broadcast mailing lists, forums, public meetings or the telephone – but with a history of govt maladministration of IT projects and of spin it is difficult to justify to the public / taxpayer even more govt comms at even more cost when the cost is fewer police officers, a worse equipped armed forces, or longer waiting lists. Yes there has to be some govt comms – but nobody has provided any proper evidence for spend on Facebook or Twitter – you wont find CEOs communicating with shareholders that way and even celebs have realised the short termist nature of twitter which is implicitly not conducive to fully formed arguments needed for proper democratic debate, even if it is great for soundbite politics. Last but not least there is the Big Brother aspect – people do not want govt intruding in every area of life, and that includes social networking sites. govt is not a social club and influence on it should not depend on it knowing your name.
rant over but the message is: less is more so what would you give up to pay for this, and why?