We've noticed people's file storage needs are growing faster than their devices' ability to deliver enough space. To solve this, we designed smart files, which behave like regular files but only download the full file from SkyDrive when you need it. Smart files allow you to always have your files with you, without using all your bandwidth or local storage.
http://channel9.msdn.com/posts/Smart...and-Windows-81

In my view, if you are always moving around from computer to computer, and logging into your Windows account on multiple computers, this will actually enhance your privacy, because you won't have your entire SkyDrive copied to every computer you use; only the files you work on during the current session will be actually downloaded to the local computer.