If you're interested in how the Chinese are observing the 20th anniversary of the Tiananmen Square massacre, said Kim Zetter in Wired, don't expect to learn about it on Twitter. Or Flickr. Or via Microsoft's Hotmail. Internet users in China say the government is blocking a host of popular Internet services to censor discussion of the June 4 anniversary of the crackdown on Tiananmen protesters.

Some social-networking websites, including Facebook, are still available, said Sky Canaves in The Wall Street Journal, and most of the sites that went down claimed they were voluntarily performing maintenance. So it's conceivable that these websites are down due to technical problems rather than censorship. Still, this outage is so widespread—everything from Microsoft's new Bing to popular Chinese microblogging service Fanfou—that it's hard to believe it's not the work of the Chinese government.

Whatever the case may be, said Stan Schroeder in Mashable, it will be hard to quiet those that want to share their thoughts about the Tiananmen Square massacre. Twitter users are busy searching for ways around the censorship. And "Twitter may be working if you’re using third-party apps to access it, such as TweetDeck."