Yes, you can use the upstream module to have nginx load-balance requests to different backends.
In the global block:
upstream backend {
server unix:/dev/shm/.php-fpm/socket;
server unix:/dev/shm/.php-fpm/socket2;
}
Or use server IP addresses or domain names, if you want the requests to go to other machines, rather than different PHP instances.
And then in the server block:
location ~ \.php$
{
include fastcgi_params;
fastcgi_pass backend;
fastcgi_index index.php;
fastcgi_send_timeout 15;
fastcgi_read_timeout 15;
fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
}
The backends can also be IP/domain names, to allow you to load-balance to other machines.