I just learned that two weeks ago a federal district court certified a question to the Washington Supreme Court:
The Court finds it is necessary to ascertain Washington law with respect to a library's public computer Internet filtering because Article 1, § 5 [of the Washington Constitution] provides broader coverage from an overly broad governmental policy than the First Amendment. Washington law does not clearly define what role a state library’s mission and functions play in analyzing whether a library’s Internet-filtering policy violates Article 1, § 5. Therefore, the Court exercises its discretion to certify the state constitutional issue(s) to the Washington Supreme Court.
The district court opinion (Bradburn v. North Central Regional Library Dist. also has more about the factual submissions so far in this case, one of the few to have actually reached the courts. ("[T]here are only three reported cases addressing Internet filter use in public libraries: United States v. American Library Association, 539 U.S. 94 (2003); Miller v. NW Region Library Bd., 348 F. Supp. 2d 563, 569-70 (M.D.N.C. 2004); and Mainstream Loudoun v. Board of Trustees of the Loudoun County Public Library, 24 F. Supp. 2d 552 (E.D. Va. 1998).)
As you may recall, the American Library Association decision didn't resolve even the First Amendment question of whether a library could continue to block adult users' access to nonobscene Internet materials. Justice Kennedy's and Justice Breyer's concurrences stressed that the Court was deciding only whether the federal law mandating filters was constitutional so long as "on the request of an adult user, a librarian will unblock filtered material or disable the Internet software filter without significant delay" (that's from the Kennedy opinion). In this case, the allegation is that librarians did not promptly unblock certain constitutionally protected material that was sought by adults, so even the First Amendment issue is still open -- as is the Washington Constitution issue that the district court is asking the Washington Supreme Court to explore.