The headline of the AppNexus job description jumps out with a question: Have you built RESTful APIs?? It's the newest requirement for job listings, already known for their acronyms requiring OOP and MVC. You not only need to be able to consume web services. Now you have to have experience creating them.
Last month Yahoo! announced BOSS, its Build Your Own Search Service, which "allows developers and companies to create and launch web-scale search products by utilizing the same infrastructure and technology that powers Yahoo! Search." The REST API allows developers to get results in XML or JSON format for web, news, and image search queries. Recently the official Yahoo! Search Blog showcased a handful of the best mashups that third-party developers created in BOSS's first month of operation.