Ironically, those remaining supernodes run on grsec'ed Linux boxes (I hope Spender gets a sizeable donation from Microsoft). They can host a considerable amount of clients, ~100000.
At the same time, the number of online Skype users jumped (http://skypejournal.com/blog/2012/04/23/skype-topped-41-5-million-concurrent-users-online-today-chart/) and can now reach 41M at peak hours.
This will likely ensure that former outages (http://articles.latimes.com/2010/dec/23/business/la-fi-skype-20101223) don't happen again, and gives MS a better control over the network.
Edit: dead link, so here is the original graph from Skype Journal:
Edit: Microsoft confirms (http://arstechnica.com/business/news/2012/05/skype-replaces-p2p-supernodes-with-linux-boxes-hosted-by-microsoft.ars):
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.I do think that this was the way to do things, and that their beliefs expressed in the last sentence are correct (if anyone cares what I think!). They didn't say how much they are going to give Spender though...