Earlier quoted context omitted.
Depends on the app platform. In the rails world Phusion Passenger (aka mod_rails or mod_rack) in combination with Apache is making inroads for serving up dynamic content. Despite the bigger footprint and other downsides of Apache, I'm hearing more and more that stability and ease of configuration of Passenger are a win. I'm only running it on a low usage backend app for the moment, but it was definitely easy to set u…
Passenger is a big win. I once ran nginx + mongrel_cluster, and while it probably had less overhead than the equivalent Apache + Passenger setup, it was more than cancelled out by the effort necessary to babysit the mongrel processes. This was also more of an issue with MRI-era Ruby and its associated memory leaks. With Passenger, I set it and forget it. Time is money.
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.