The features outlined to be included in 3.4 have been outlined in detail in this article. Although there is a slideshare which will give you a nice, easy slide by slide breakdown of what Joomla wants to accomplish with 3.4. by David Hurley
David says that the goal with 3.4 is simple - "Beginning the Transition” with Joomla 3.4 we are going to begin the process of creating a lightweight and powerful application which can be adapted easily for a variety of use cases.
