On April 17, the United States Court of Appeals for the District of Columbia issued a temporary injunction, enjoining the posting of the NLRB poster.  The Circuit Court of Appeals issued a briefing schedule, which will result in an oral argument sometime in September 2012.  Given the current schedule, it is unlikely that a ruling on the posting will be issued before this November, at the earliest.  

The case being heard by the D.C. Circuit is the one brought by the National Association of Manufacturers, among others.  The Court, in its very brief Order, noted the very recent holding by the United States District Court for the District of South Carolina, holding that the National Labor Relations Board lacked the authority to promulgate the notice-positing rule.