The Microsoft Update patches were merely a catalyst — a trigger — for a series of events that led to the disruption of Skype, not the root cause of it.
The high number of post-update reboots affected Skype’s network resources. This caused a flood of log-in requests, which, combined with the lack of peer-to-peer network resources at the time, prompted a chain reaction that had a critical impact.
Unfortunately, this time, for the first time, Skype was unable to rise to the challenge and the reasons for this were exceptional.
Kudos to Skype for finally explaining the problem in a bit more detail. At this moment, there are currently 8,436,405 people online with Skype. This extraordinary number does represent a significant responsibility and obligation from the company to its users.
Although software failures happen despite the best of intentions, customer service and communications are another matter entirely. Skype, I give you a "C" grade on your handling of this incident. Next time, can we please have more information sooner?
[Thanks to fellow ZDNet blogger George Ou, for describing his analysis of the outage to me in online chat, which ironically took place using Skype.]