It looks like Apple “needs” to upload even your unsaved documents to its servers to make the newly introduced Continuity “feature” work.
Also it seems Apple silently uploads names and email addresses of all the people you correspond with–no, not only the ones in your address book–just to have a “consistent” experience when displaying recent addresses.
It scares me how little their customer’s privacy must be worth when they choose (these are not accidental data “leaks”) to silently violate them in order to provide comfort features.
It seems there is at least a hidden configuration option to turn this behavior off:
defaults write NSGlobalDomain NSDocumentSaveNewDocumentsToCloud -bool false