Vercel has launched Next.js 12.1, a new version of its popular React framework that includes on-demand Incremental Static Regeneration (ISR), allowing developers to build real-time dynamic websites with statically generated performance. This feature enables building real-time guestbooks and other dynamic sites without needing dynamic routes, using webhooks to trigger page rebuilds in real-time. The example uses Vercel, Next.js, Svix, and Clerk to demonstrate how to implement this functionality, showcasing the potential of combining these services to achieve high-performance and automation capabilities.