the same here. As far as I know /usr/local/bin owns root ie only root is allowed to write something in that directory. All other users/groups should only read and execute stuff in there; otherwise it's a security hole.
Actually the [homebrew][1] project seems to have other ideas, which one may or may not agree with.
But in any case it is probably not a good idea to make assumptions or to impersonate the local hard disk sherif.
Gerd