How does the Windows Azure AppFabric Caching service relate to Windows Server AppFabric Caching?
They are built on the same underlying technology platform. The Windows Azure AppFabric Caching service is a service that you can use on Windows Azure. For Windows Azure AppFabric Caching, Microsoft has created all of the underlying cache infrastructure for you and automated the provisioning and management of the cache on Windows Azure). For more information, see Caching Service (Windows Azure AppFabric) on MSDN.