The Cabinet Office has now published guidance for civil servants for blogging and participation in online sites.
How the Civil Service Code applies to online participation
The Civil Service Code applies to your participation online as a civil servant or when discussing government business. You should participate in the same way as you would with other media or public forums such as speaking at conferences.
Disclose your position as a representative of your department or agency unless there are exceptional circumstances, such as a potential threat to personal security. Never give out personal details like home address and phone numbers.
Always remember that participation online results in your comments being permanently available and open to being republished in other media. Stay within the legal framework and be aware that libel, defamation, copyright and data protection laws apply. This means that you should not disclose information, make commitments or engage in activities on behalf of Government unless you are authorised to do so. This authority may already be delegated or may be explicitly granted depending on your organisation.
Also be aware that this may attract media interest in you as an individual, so proceed with care whether you are participating in an official or a personal capacity. If you have any doubts, take advice from your line manager.
Simon Dickson has more.