Marcus, one of my QUT colleagues, pointed me to the heartbeat post by Joosep pointing to the problem:
UPDATED 14:02 GMT: Some of you may be having problems logging into Skype. Our engineering team has determined that it’s a software issue. We expect this to be resolved within 12 to 24 hours. Meanwhile, you can simply leave your Skype client running and as soon as the issue is resolved, you will be logged in. We apologize for the inconvenience.
Additionally, downloads of Skype have been temporarily disabled. We will make downloads available again as quickly as possible.
Subsequently, Brad Stone at the New York Times reported on the issue, identifying a software bug at the heart of the issue which had amazingly lain dormant since the start of the Skype service in 2003. And yes, the mention of conspiracy did arise, but I’ll leave the rest of the blogosphere to contemplate that.