This week's book giveaway is in the OO, Patterns, UML and Refactoring forum. We're giving away four copies of Refactoring for Software Design Smells: Managing Technical Debt and have Girish Suryanarayana, Ganesh Samarthyam & Tushar Sharma on-line! See this thread for details.
I think that sentence is misleading at best. While REST APIs can make use of existing HTTP caching mechanisms, that may or may not be a good reason to prefer REST over SOAP. It is unlikely to be the most important criterion when making the choice. Furthermore, HTTP-based caching is less prevalent than other forms of caching that can be used by both approaches.