Next version of Elementary OS codenamed "Luna" will be based on just released Ubuntu 12.04 LTS "Precise Pangolin" and it is going to bring about a number of really interesting changes, new notification system being one of them.
Video Demo of Elementary OS's New Notification System
Elemenatry OS "Luna" has not yet been released and features like these are supposed to be polished and further improved before the final release. From the initial looks of it, I think I am going to really like the next Elementary. Also, this new notification system looks like something Ubuntu can emulate in their future releases. Notify-OSD, at the moment, looks terribly designed and executed. [Video demo by WilleoSoeurs]