According to the publisher (Harper Collins) the book will definitely be released on April 30th. Apparently the CIA approved Tenet's material for publication yet to date has still refused to declassify the Helgerson IG internal review report. Will Tenet's account cover some of the same ground reviewed in the Helgerson report? Without question. So what gives? One can guess that Tenet's account will leave out some of the failures mentioned in the IG report.
Fairly recently, Sen. Wyden added an amendment to the Improving America’s Security Act of 2007 bill which calls for the declassification of the Executive Summary of the Helgerson IG report. Last I checked the bill passed the Senate and is awaiting a House vote. This step was taken because the CIA Director (Goss then, Hayden now) and the DNI (Negroponte then, McConnell now) have refused to declassify the report.
Basically what we have (with CIA approval of Tenet's book) is a double standard that displays an appalling level of contempt for the American public.