CodeGear has published on the fifth and last of my series of white papers introducing Delphi 2009 and extracted from my book Delphi 2009 Handbook (available in printed form from Titled "The new DataSnap in Delphi 2009" the white papers covers the totally renewed version of DataSnap, originally called MIDAS, that is Delphi's native three-tier architecture. 

As for the past papers, you can find more complete information in the book (available in PDF format to registered users of Delphi 2009 and in printed form on, from which the white paper was abridged.