From the Washington Post:

As women gain visibility in the blogosphere, they are targets of sexual harassment and threats. Men are harassed too, and lack of civility is an abiding problem on the Web. But women, who make up about half the online community, are singled out in more starkly sexually threatening terms -- a trend that was first evident in chat rooms in the early 1990s and is now moving to the blogosphere, experts and bloggers said.