For Habermas, the public sphere is the arena in which public opinion is formed, independent of economic or government influence. The public sphere depends on the flow of information and the ability to debate rationally. And so it may be variably realized depending on the governing regime: Habermas advances a story of rise and decline.
Reviewing the notion of the public sphere, sociologist Frank Webster writes:
Information is at the core of this public sphere ... In perhaps its most elemental form, parliamentary debate, and the publication of a verbatim record of its proceedings, expresses a central aspect of the public sphere, though clearly the role of communications media and other informational institutions such as libraries and government statistics offices can be seen to be important contributors to its effective functioning.[Theories of the Information Society. 2nd Edition. p. 163]
Interestingly, Webster goes on to consider public libraries in some detail.
The public library network is arguably the nearest thing we have in Britain to an achieved public sphere. [Theories of the Information Society. 2nd Edition. p. 176]He suggests that public libraries in the UK feature three relevent public sphere elements: (i) they make information freely available to everybody, (ii) they are publicly funded but are free of political influence, and (iii) they are staffed by professional and expert staff who provide a service without prejudice or hidden motives.
Incidentally, it is refreshing to see this discussion of libraries in Webster's book. Libraries do not always figure in discussions of the 'information society' within the non-library literature.
(Prompted by Alane's mention of Habermas the other day.)