I've been using NGinx/Mongrel for most of my large deployed apps, but am working to get things moved to Passenger (and Apache, natch), simply for the ability to do a graceful restart on most code changes. For large apps, the ever expanding mongrel footprint and slow restarts is becoming too much to bear.

So for me, Nginx has a lot to offer over Apache, but with the rails deployments I've been working on mostly, it's no longer enough.