This week's book giveaway is in the OCAJP 8 forum. We're giving away four copies of OCA Java SE 8 Programmer I Study Guide and have Edward Finegan & Robert Liguori on-line! See this thread for details.
It's really a development paradigm where the focus is on creating reusable services that can be exposed over open platform-neutral protocols such as REST or SOAP. The focus is on making services that perform fairly discrete operations. Wikipedia provides a pretty good description.