Central banks are no longer discussing artificial intelligence in the abstract: the European Central Bank's staff nowcast inflation with web-scraped price data and large language models, the BIS Innovation Hub is running projects on information collection and payments oversight, and Federal Reserve research argues that AI changes the environment for policy without redefining its objectives. For economists and central bank analysts, the practical question is comparative: which applications exist, what data and methods they rely on, and what trade-offs they introduce. This article maps four documented uses across the ECB, BIS, and Federal Reserve system, then examines what AI diffusion means for the indicators and frameworks that monetary policy has traditionally depended on.