Activision Blizzard has won a victory over Worlds Inc, which has been leveraging its patents on basic virtual world principles -- like the ability to chat with other users in a virtual environment -- to sue MMO companies like Blizzard and Second Life makers Linden Labs. Patent trolling can be big business and, indeed, seems to be the primary business that Worlds Inc is in these days. However, they may be running out of luck in this case, as the latest ruling suggests the patents are invalid because they describe things already in public use before they were filed.
However, this ruling is certainly not the end of the ongoing legal drama involving Worlds, which has lauded the ruling as a clear victory for itself. But with the Supreme Court currently considering whether to take stronger action against patent trolls, which may make it easier for sued companies to recover legal fees from patent trolls (and thus deter these sorts of lawsuits), it may be harder for Worlds to find traction on such lawsuits in the future. We'll have to keep watching to see just what happens between Activision Blizzard and Worlds, but it seems unlikely that they'll manage to recover from this ruling.
If you want all the details, check out the writeup on Gigaom or, if you're fluent in legalese, read the decision yourself.