Twitter the microbloging site was hacked recently. If you mouse over malicious tweets you may get infected, even if you don't click them open. The bug redirects users to third-party websites without their consent. Twitter has successfully patched the "XSS attack," according to the Web site's status blog.
The repair is complete and the site is back up and running. The hack affects users of the Twitter site, and hasn’t impacted users who use third-party applications, such as Tweetdeck.