Several of the people whom I have set up with laptop/netbook systems, and loaded Skype (against my advice, but it's their computer) called me yesterday, saying that they could not log in to Skype. A quick check of some common blogs, the Skype Community and finally the Skype "Heartbeat" blog confirmed it. There was/is something wrong with the Skype "Sign-in Server", apparently world-wide. If you are/were already signed in, things were apparently ok (at least as ok as they get on Skype), and you could make calls. If you were not signed in you were out of luck. Period.
It is not clear to me whether the situation still exists, or has been remedied. The last thing in the Skype "Hearbeat" blog says:
[2009/01/12@2002UTC] We've made some changes which should improve things. Stand by!
As soon as I have more information, I'll update this post.
Of course, after that there is nothing, so is it fixed, or is it still not possible to log in? I refuse to contaminate any of my systems with Skype, so I don't know. I assume that I will hear before long from one or another of my friends who called yesterday. I also assume that we will not ever hear any plausible explanation from Skype about what happened, just like the last time this happened world-wide for FOUR DAYS, there will just be a lot of blather about how much they "love their customers", and they are "working very hard to make sure this doesn't happen again". Apparently not hard enough.
When you consider using Skype for communication, and especially if you consider using it for business communication, think about situations like this. If you are going to play "you bet your business" you had better make sure that you have reliable partners.