The only ubuntu stack script listed that comes up for LEMP is mine.
It has the option of installing the latest stable version of nginx, however it doesn't automatically configure nginx to talk to php since everyones configuration will be different you're expected to do that bit yourself.
Have a browse of
http://wiki.nginx.org/ for tips on configuring it and if you do use the nginx from the ppa then /etc/nginx/nginx.conf does contain a commented out section for talking to php.
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