Shebang line in drush should point to /usr/bin/env

/usr/bin/env | /bin/env :
Will give the actual location of a binary.
thus when a program is distributed, it will use the php in the users path rather than some other php... allows for nonstandard ( ie macports /opt/local/* or fink /sw/whatever )
I might send a patch with a fix .. depending... on time constraints