On January 12, the U.S. Supreme Court heard Reed v Town of Gilbert, Arizona. This is not an election law case, but any case involving discriminatory treatment and free speech has the potential to affect election law. The issue is a town ordinance that says some types of signs may remain on the public right-of-way for months and may be large, whereas other types of signs must be small and removed very quickly after the event that the sign is advertising. See this story, which suggests that the town ordinance will be held unconstitutional.
UPDATE: here is the transcript of the oral argument. Thanks to HowAppealing for the link.