Hormel, makers of SPAM, is suing SPAM ARREST, purveyors of spam-blocking software, according to this Seattle Times article.
Here is the text of Hormel v. Henson, wherein Hormel could not stop Henson from using Spa’am as a name for a wild boar in a Muppets movie. Here are the spam haiku archives. Here is the Monty Python spam sketch.
And it is interesting to note that Spam Arrest owns a federal trademark registration for SPAM ARREST (disclaiming SPAM).