A couple of years ago, a court ruled that the heirs of Jerry Siegel, co-creator of Superman, owned the rights to Superboy, a later version of Superman that Siegel created. Almost immediately, DC Comics eliminated their latest character with the Superboy name; and an animated version of the Legion of Superheroes featuring the Teen of Steel called him Superman, not Superboy.
Now comes a court decision with wider-reaching consequences: a Central District Court of California judge has ruled that the heirs of Siegel own a portion of the copyright for Superman. In 1997 the heirs served copyright termination notices under provisions of a 1976 law that permits heirs, under certain circumstances, to recover rights to creations. The court ruled that as of 1999, the Siegel heirs owned a piece of the American copyright to the Man of Steel. Further, the ruling leaves the possibility that in 2013, the heirs of Superman's other creator, Joe Shuster, may do the same.
Note that the years since 1999 have been lucrative ones for the licensors of Superman. Media exploitation of the Man of Tomorrow in that time frame includes the long-running TV series SMALLVILLE; the aforementioned Legion of Superheroes cartoon; the SUPERMAN RETURNS movie; the recent Justice League cartoon; direct-to-video animation works, including SUPERMAN:DOOMSDAY and THE NEW FRONTIER; and lots and lots of toys, clothes and assorted knicknacks. A piece of all that gold may be enough to buy the heirs their own Fortress of Solitude. (Whether they can obtain that, though, depends on some complicated issues -- such as how much of the merchandising and licensing is due to elements that appear in Superman's debut, in Action Comics #1; and how much is due to later elements of the character -- as well as his trademark, which DC parent Time-Warner likely owns clear.)
Here's a copy of the court's opinion. And what an opinion it is -- it not only quotes declarations from such comic book historians as Mark Evanier and Jim Steranko, but also sets forth black and white and color illustrations.