Skype may be facing a minor security controversy at the moment, but it appears Microsoft has already been making some behind-the-scenes changes to improve the service by altering Skype's use of "supernodes." In prior versions of Skype, machines that met the proper bandwidth and processor specs could be promoted to supernode status, where they would serve as peer-to-peer clients for distributing information about which Skype users were online at a given time. Security researcher Kostya Kortchinsky writes that he had discovered as many as 48,000 supernodes in his exploration of Skype's architecture, but that in the last month that number has dropped to approximately 10,000. Furthermore, whereas supernodes had previously been machines in the wild, now all of the discovered supernodes are machines hosted by Microsoft and Skype, running a security-hardened version of Linux.
As far as what this means for the average Skype user, Kortchinsky told Ars Technica that the move away from the P2P implementation "will definitely bring more stability and security and it may also bring more clients" to the service. Whether the ever-changing carousel of Skype's desktop clients will get the same attention to detail still remains to be seen.
Update: Skype has confirmed the use of its own hosted supernodes, with Mark Gillett, the company's CVP or product engineering and operations, providing the following statement.
As part of our ongoing commitment to continually improve the Skype user experience, we developed supernodes which can be located on dedicated servers within secure datacentres. This has not changed the underlying nature of Skype's peer-to-peer (P2P) architecture, in which supernodes simply allow users to find one another (calls do not pass through supernodes). We believe this approach has immediate performance, scalability and availability benefits for the hundreds of millions of users that make up the Skype community.