How can I turn ~/Documents into a symlink? I keep my Documents in an encrypted directory in Dropbox (~/Dropbox/encrypted), which I then mount at ~/clear when I log in.  On my other Macs, I have change ~/Documents to a symlink that points at ~/clear, but trying to do the same on a new Mountain Lion machine doesn't work:

Pertinax:~$ pwd
/Users/drew
Pertinax:~$ ls
Desktop         Dropbox         Music           README.markdown tmp
Documents       Library         Pictures        bin
Downloads       Movies          Public          clear
Pertinax:~$ ln -sf clear/Documents .
ln: ./Documents: Permission denied
Pertinax:~$ ls -l@hd Documents
drwx------+ 3 drew  staff   102B Apr  5 15:02 Documents
Pertinax:~$ xattr -l Documents


It doesn't appear to have odd permissions or extended attributes, so I'm stumped.  I don't recall what I had done previously to make this work on my Lion and prior machines, or if I did anything special at all.
All of the default subfolders of your home have an ACL set to "everyone deny delete" (ACLs can be viewed with ls -le and stripped with chmod -N)

ACLs still don't affect a command run as the superuser.