I am in the process of installing a pre-release version of Jaunty Jackalope on a virtual machine. There's few significantly new developments at this point that bear remark, except perhaps for the new timezone selection screen pictured above.
This pre-release version still uses the Intrepid background theme. I was expecting the default file system to be ext4, but apparently, it still uses ext3 under a standard installation.
More to follow in a little while.