The American Civil Liberties Union has posted information for federal employees regarding their rights to freedom of speech. An excerpt:
The Supreme Court has stated clearly that public employees cannot be fired for speaking on issues of public concern as private individuals. Practically speaking, this means that – with the possible exception of certain high-ranking government officials – an employee can speak on personal time and in a personal capacity about matters that affect the public.
Read the entire article, Government Employees Get to Have Opinions, Too, on the ACLU website.
Note that additional restrictions may apply to federal employees posted overseas. Read more about the Hatch Act and Foreign Affairs Manual here.
On a related note, at least one private Twitter account has been set up, apparently by Department of State employees. Check out this “rogue” account, @AltStateDpt.