safe_mode redesign

Is anyone up for a discussion on the redesign of safe_mode? I would like to start working on this sometime soon, and I have a lot of ideas, but I know this is going to be something of a large debate. Some of the new features I think would benefit php include: * safe_mode_hide_env_vars - will allow extra protection on removing environmental vars from hosted users ( I actually have a patch for this but I have been waiting on it to discuss the redesign) * User configurable policy - safe_mode could have configuration directives to specify exactly what checks are desired * Virtual Chroot - the ability to perform a chroot to a virtual host directory structure, so that a hosted user can not access anything outside of their directory structure. * Shared Directories - The ability to specify a list of paths that are shared amongst all hosted users. This would allow certain extensions (gd, oracle, etc) the ability to access the needed datafiles without failing a safe_mode check. Any comments, suggestions, other ideas? -Jason