For one, replicating information across multiple data centers is considered a good idea in case one data center becomes impaired by a natural disaster.
Netflix saves money and time and offers higher quality streaming by replicating and caching its content at data centers across the U.S. (and now Canada) to be as close to its customers as possible.
Companies like FluidOps make replicating all levels of a virtual landscape--the data, database, application, and operating system--a one-click operation.