http://www.pcworld.com/article/id,136048-c,webtelephonyconferencing/article.html
Skype, the popular VOIP service is currently down and the outage may last for a day. If you’re in Skype stay in, as the problem appears to be related to authentication.
Update (8/20): Skype says the outage was due to Microsoft Patch Tuesday, and a bug in their algorithm.