The most exciting feature in 3.4 (at least in my opinion) is the addition of asyncio to the standard library, which aims to provide a standard event loop which libraries like Twisted can then use to make themselves interoperable with other async Python solutions:

http://www.python.org/dev/peps/pep-3156/

"The event loop is the place where most interoperability occurs. It should be easy for (Python 3.3 ports of) frameworks like Twisted, Tornado, or even gevents to either adapt the default event loop implementation to their needs using a lightweight adapter or proxy, or to replace the default event loop implementation with an adaptation of their own event loop implementation. (Some frameworks, like Twisted, have multiple event loop implementations. This should not be a problem since these all have the same interface.)"