"In the landscape of today’s megaservices, Hotmail just might be Mount Everest. One of the oldest free Web e-mail services, Hotmail relies on more than 10,000 servers spread around the globe to process billions of e-mail transactions per day. What’s interesting is that despite this enormous amount of traffic, Hotmail relies on less than 100 system administrators to manage it all." continue reading here.
The scaling of megaservices!