According to Karl Kessler's article in SAPInsider, the New ABAP Editor should be part of the Sneak Preview of NW 2004s:
"To get a taste of the new ABAP Editor and Debugger for yourself, simply download the latest Sneak Preview version of the ABAP application server (based on SAP NetWeaver 2004s), available on the SAP Developer Network
(SDN) at www.sdn.sap.com/irj/sdn/downloads."
Maybe I am missing something, but in my version there is no radio button for "Front-End Editor (New)".
Will the editor only be available with SP8?