The flipside of social media's ability to rapidly spread content is that scams, viruses and malware spread at a much faster rate: from the trusted connections that allow Facebook scams to propagate, to the abundance of Twitter issues in recent months.
Today's scam: a video site called "Juste.ru" (do not visit this site) has successfully spread thousands of spam links through Twitter. The messages read: "Best video:" followed by a link to juste.ru. Users who clicked this link are reporting that their accounts are then used to Tweet the link without their knowledge, implying that the site steals Twitter credentials. Twitter itself has just put out a warning to avoid the links, which are malicious.
Bottom line: avoid clicking any links on Twitter to "juste (dot) ru", and if you find your account posting these links, run a full virus/malware/spyware scan, change your Twitter password and clear your browser cookies.