If you like cloak-and-dagger stuff, you're going to love the direction that the "Skype Back Door" rumor is going. It seems that some people are now saying that the four day world-wide Skype outage last August was not caused by Windows Update, but was in fact Skype building in a back door for government monitoring of Skype calls (source, more speculation).
I have no idea if this is true or false. My opinion of Skype's technical staff is such that it would not surprise me one bit that they would take four days of down time to accomplish something like this, though. The one thing I can say for certain is that I have always thought that outage was very suspicious. I was pretty deeply involved in the Skype User Forums at that time, and I said repeatedly and publicly that the "explanations" that Skype gave then were silly and inadequate. In fact, that outage and the cover-up and misinformation surrounding it were the beginning of the end for me with Skype.
One thing is for certain, though. I said then, and I will say again now, we will probably never know the real truth about what happened with that outage.