Here is a brief interview
with Werner Vogels
on Amazon and SOA which has some important take aways particularly around designing for simplicity, maintaining customer focus, being business driven and technology agnosticism. Amazon has evolved from a single server, single database environment to a multi-server database platform serving millions of customers. Along the way they discovered that a service oriented architecture provided the flexibility and agility to support their business goals. Amazon didn't attempt to retrofit a set of technologies or an architecture approach into their business they actually found that such an approach helped them to grow their business. To facilitate the magnitudes of scale and reliability they moved from a centralized mainframe platform to a one built on distributed components. Nothing new but always nice to heat about the practicality of SOA solving real world problems.