Observable 2.0 introduces a new static site generator called Observable Framework, which allows developers to build fast and beautiful data apps, dashboards, and reports. The framework combines JavaScript on the front-end with any language on the back-end for data preparation and analysis. It solves the 'last mile' problem of data apps by precomputing data at build time, making pages load instantly. Observable Framework is free, open-source, and allows for customization and hosting on any platform.