I think I did not make my point clear enough. It is trivial to make it inaccessible to programs who assume that it is easily accessible. I did not mean to include solely malicious programs.

If you stick your addressbook into a truecrypt container 100% of programs (i know there is no 100% security, but there is not enough space to spell out all 99.999999s) will not be able to access it anymore without you unlocking/mounting it first. Thus, requiring your permission.