This Mercury News article describes a mafia-like organisation emerging in one of the The Sims Online cities. Apparently, an attempt to create some order in the shape of a shadow government got out of hand and resulted in a rather less benevolent "family." I tried to find out more about this, but after a lot of digging I only turned up the website of Mia Wallace, the city's most popular character -- and capo di tutti capi -- referred to in the article. The only other online references to the affair appear to be dozens of weblogs linking to the Mercury News article.
So I had doubts any of this actually happened, until I read this presentation and Q&A by Will Wright, creator of the game, where he describes the events (search on the page for the word "curious"). Of course, such governmental-style groups aren't new in freeform open-ended games, as this MetaFilter thread describes. But the fact there are more commercial and high-profile games in which this can happen, rather than obscure MUDs, is a more recent development. Which leads on to such events being reported in increasingly mainstream media and thus becoming "events" in the real world.
In related news, Clay Shirky posts some interesting links to Julian Dibbell's ever fascinating weblog in which he documents his attempts to make a real world living by trading in Ultima Online. Also, there's a link to this New York Times article about a guy spending seven hours a day in his preferred virtual game world.
Moments to watch for: news of game events appearing on television news. It wouldn't surprise me if this has already happened in an amusing "And finally..." spot (anyone seen such a story?), but serious news items seems inevitable.