I think you are over-reacting. Regardless of if it is in the TOS, Dropbox and every other company on American soil has to follow the rules set forth in the new TOS. If you want to ensure privacy of files stored on Dropbox I suggest you encrypt them with Truecrypt, or Keypass. Both tools work well with Dropbox. I for one would not suggest leaving my encryption implementation, key management and so forth to an unsupervised third party anyway!