Not only is it not a rumor -- Russia's President Medvedev is pissed about it (or so he says):
The BBC reports: "Russian President Dmitry Medvedev has condemned as "outrageous and illegal" a cyber-attack on a popular social networking website that hosts his blog. The LiveJournal site was hit by a denial-of-service attack on Wednesday. The site crashed after being bombarded with messages from thousands of infected computers, an expert from the Kaspersky Labs computer company said. Russian media say a similar attack has now hit Novaya Gazeta, a newspaper often critical of official policies."
BBC
http://www.bbc.co.uk/news/world-europe-13011540 Medvedev's Livejournal blog
http://community.livejournal.com/blog_medvedev/