You can't catch swine flu on Twitter, said Robert X. Cringely in PC World, but you can sure get caught up in "the swirl of misinformation and panic that has flooded everybody's favorite microblog." Twitter is helping to spread unnecessary hysteria around the world as millions of people cram their worst fears into 140 characters.

Bash Twitter all you want, said Kit Eaton in Fast Company, but the swine flu outbreak has provided a clear example of "Twitter's power to spread information." I didn't hear about the problem from TV or radio—I got the news on Twitter. Panicky tweets are unfortunate, but they're "not Twitter's fault," plus they're offset by plenty of useful information and calls for calm.

There's definitely some useful information streaming in at Twitter," said Stephen Wildstrom in BusinessWeek. The trouble is that for every tweet containing a link to a respectable information source, there are "at least 10 that are repetitive, silly, pointless, or simply wrong." If this is a test of Twitter's usefulness, it's "failing badly."