Yesterday, worldwide users of Twitter, Facebook, LiveJournal, Google’s Blogger, and YouTube faced problems accessing their accounts. This morning, they got a partial answer as to why: The sites were down due to a massive cyber attack that was apparently meant to silence a political dissident or group named after a town in the Republic of Georgia called Cyxymu (via CNET News). Also silenced in the attack was Denver-based, a real-estate site. “When you’re doing things like launching a blog for a day, a marketing initiative or telling people what you’re doing tonight, it’s really hard to get the news out because that’s your network,” Erika Napoletano, director of communications for the company, tells The Denver Post. Social media enthusiasts happened to be gathering last night in Denver for a conference sponsored by Mashable, a popular blog network. The big question on everyone’s mind was, “‘What’s going on?'” as Ben Parr, an associate editor for Mashable and a regular contributor, puts it. Outages lasted hours in some cases in the denial-of-service (or DoS) attacks. The answer seemed to come today as reports proliferated around the globe about Cyxymu. Twitter co-founder Biz Stone, however, has declined to speculate about who was responsible for the attack (via Britain’s Telegraph). “Over the last few hours, Twitter has been working closely with other companies and services affected by what appears to be a single, massively co-ordinated attack,” he says.