To my mind, a PLE is as the acronym suggests, an environment for learning that is personal. Therefore, it can be made up of a network or networks, applications, tools, documents, contacts, the work of contacts, etc etc. The term has arisen surely as a response to VLE where as you have mentioned, there is a sense of ownership of a body to which a user is subscribed. This means that all those elements of the environment must be stored within that one environment rather than one of a possible set of environments which could and often do make up a PLE. Catch my drift?!?!!?