But actually, you could have setup a pure Python server instead of nginx for the last 10 years with twisted.
Not that you should not consider uring nginx anyway: it deals with caching, load balancing, has great tutorials, it's battle tested, and has tons of pluging.
Sure, I mentioned Tornado a few minutes before you posted this. Twisted obviously counts too, I dislike the non-PEP8 coding style it uses but that's off topic. I love Python's non blocking features, they're just not in the mainline VM right now. Here's hoping for a libuv or whatever else non blocking Python 4 VM / stdlib.
But actually, you could have setup a pure Python server instead of nginx for the last 10 years with twisted.
Not that you should not consider uring nginx anyway: it deals with caching, load balancing, has great tutorials, it's battle tested, and has tons of pluging.
But performance wise, WSGI is not Python.