Does the fastcgi permissions in nginx work like those in Apache, in which it runs with permissions of the script owner?
From what I see it runs with the permissions of the web user. Can it be changed to run with only the scripts owners rights?
From what I understand suphp achieves this by using normal CGI instead of FastCGI which makes it far slower. There is also no nginx module that can do this. Generally Nginx isn't really suited for being used stand-alone on a shared hosting server.