The blog post discusses the implementation of a hand-raising feature in Daily Prebuilt video calls using the newly introduced setUserData() method in the daily-js API, allowing participants to indicate their desire to speak by raising a virtual hand. This feature synchronizes the states of participants' hand-raising across the app and ensures the order of raised hands is visible to all, addressing challenges like multiple users raising their hands and determining who raised theirs first. The post outlines the steps to set up a local development environment using React and JavaScript, detailing the creation of two custom hooks, useHandRaising and useHandRaisingQueue, to manage hand-raising states and queues. Additionally, it highlights the integration of these hooks into the video app components to display hand-raising indicators and queue positions, enhancing the interactive experience by showing badges on video tiles. This implementation showcases the versatility of the setUserData() method, encouraging developers to explore creative applications of this new API feature.