This tutorial by Miguel Grinberg explains how to send scheduled SMS notifications in a Node.js application using the Twilio Programmable Messaging service. The tutorial covers the requirements, including having a Twilio account and a smartphone to receive SMS, buying a Twilio phone number, configuring a Messaging Service, setting up a Node.js project, and sending a scheduled SMS with Node.js. The author provides step-by-step instructions and code examples to help readers implement message scheduling in their applications.