Surprise! Yesterday, after deep and thoughtful analysis (i.e. a different political party appointed the majority), the NLRB overruled Register Guard. That case is Purple Communications. The NLRB describes its decision in a nutshell:
[W]e decide today that employee use of email for statutorily protected communications on nonworking time must presumptively be permitted by employers who have chosen to give employees access to their email systems.And now, the law is settled . . . until at least 2016. As Dan Schwartz blogged: "It's not right or wrong. This is just how the NLRB works."