Pivotal Web Services are deployed to the Amazon EC2. They run in the US-East-1 region and are spread across multiple availability zones. If you run multiple instances of the application, PWS automatically handles distributing them across multiple availability zones. PWS tries to distribute the applications on the different availability zones but that in not always guaranteed.
At present, PWS does not run in any other Amazon Web Services regions such as in Europe or Asia, and there is no way for a PWS user to select a different region.