Tim O'Reilly's presentation at the Web 2.0 Expo discusses the evolution of the internet as a platform and its implications for businesses, emphasizing the interconnectedness of various technologies and services. He highlights major players like Google, Microsoft, and Apple, examining their strengths and weaknesses within the context of an increasingly cloud-based and commoditized environment. The talk warns against taking the open web for granted and advocates for recognizing the collaborative nature of development, akin to an ecological system.