This press release announces Activision Publishing is suing Worlds Inc. and Worlds Online Inc. for patent infringement in the Central District of California. Or rather counter-sues, as Worlds Inc. already sued them for the same thing in March. If multiple suits over "patent infringement" sound to you like this is going to be inscrutable to a non-lawyer/non-techie, you are correct:

In the suit, Activision claims that Worlds has infringed, and continues to infringe, U.S. Patent No. 6,014,145 entitled “Navigation with optimum viewpoints in three-dimensional workspace interactive displays having three-dimensional objects with collision barriers” and U.S. Patent No. 5,883,628 entitled “Climability: property for objects in 3-D virtual environments.” The contested product is software distributed by Worlds called "Worlds Player."

Worlds Inc. filed a patent infringement lawsuit against Activision Blizzard, Inc., Blizzard Entertainment, Inc. and Activision Publishing, Inc. on March 30, 2012. That lawsuit is pending in the U.S. District Court for the District of Massachusetts.