Jeremy Glassenberg's talk at the API and IPA Meetup in March 2020 highlights the evolution and best practices of embedded integrations in popular web services. Initially, attempts like iGoogle and OpenSocial failed due to a lack of consumer demand and poor execution, but the rise of marketplaces demonstrated how engaging user communities can lead to successful integrations. Companies like Gmail and Trello have leveraged these insights to enhance their platforms by allowing third-party developers to create value-added services. Effective embedded frameworks follow a marketplace model, focusing on customer retention by offering consistent user experiences and simplifying developer engagement. Glassenberg emphasizes the importance of providing UI components and facilitating developer management through tools like manifests and dev portals, as seen in platforms like Shopify and Trello, which ultimately enhance user experience and drive business growth.