File lockers don't share your files with other people. They share your files with you when you're out goofing off and suddenly have to make a call or send an email using information in an electronic file you probably left back in the office.
Neither Dropbox nor Microsoft SkyDrive make any claim to ownership or the rights of ownership.
Dropbox warns that it is allowed to delete content that's pirated or illegal, to check for illegal files in your account and might give up usage data to police under the right warrants or subpoenas.
Microsoft reserves the right to mash or manipulate your data, but only enough and in ways required to make them available on SkyDrive. ("…You hereby grant Microsoft the right, to use, modify, adapt, reproduce, distribute, and display content posted on the service solely to the extent necessary to provide the service.")
Neither will be responsible if you post pirated, obscene, stolen Top Secret documents; both will delete them if they find them. Neither will redistribute or create derivative works from your content.
Those are rights Google reserves for itself.
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