In figuring out how to set up my blog, I learned that some public libraries may be allowing the public to post to the library's blogs.
Egad - not a good idea. Public library blogs can be great - to get library information out there. But any public library that allows users to post to their blogs can be opening up a legal minefield. Once a library opens its doors to one user's post, it is basically opening its doors to all, or should be. If a library denies a post based on its viewpoint it will almost certainly lose a First Amendment lawsuit. If it denies a post based solely on its content, it might lose as well.
One city even lost a lawsuit over not adding a link on its webpage to an alternative newspaper that was critical of the city.
On the other hand, if a library has already opened up the forum and then closes it to the public, that is generally acceptable. In a recent library case, a gay newspaper was distributed on a front lobby table along with other free publications. When the library got complaints, it restricted the table to government and library-generated publications. The court found that the table in the lobby was a hybrid forum: a cross between a limited and a nonpublic forum. Closing the forum affected both gay and non-gay interests equally, and was acceptable. See Gay Guardian Newspaper v. Ohoopee Regional Library System, 235 F. Supp. 2d 1362, 2002 U.S. Dist. LEXIS 23970 (S.D. Ga., 2002), aff'd 2003 U.S. App. LEXIS 27395.
ADDED LATER: Discussion continues in later post here