I've been using nginx+memcached for about 2 years on a high traffic site in production. It's been pretty great and runs without a hiccup. However bear in mind t

I've been using nginx+memcached for about 2 years on a high traffic site in production. It's been pretty great and runs without a hiccup. However bear in mind that Varnish is far more capable as nginx's memcached integration is fairly simplistic. You'll have to manage all your keys in the application layer as all nginx can do is send a certain request to a certain key and failover if it's not found. Varnish ACLs allow much finer control. Also, I've come across benchmarks that say Varnish is faster. I just don't want to deal with a complex setup for something that gets the job done. (Job = lower the load on the app server)