UPDATE
Apparently it's not going to happen.
I'm leaving the post here anyway, as I hope the code will resurface as extension, on PGXN maybe?
On 14th of May, Stephen Frost committed patch:
Add pg_audit, an auditing extension This extension provides detailed logging classes, ability to control logging at a per-object level, and includes fully-qualified object names for logged statements (DML and DDL) in independent fields of the log output. Authors: Ian Barwick, Abhijit Menon-Sen, David Steele Reviews by: Robert Haas, Tatsuo Ishii, Sawada Masahiko, Fujii Masao, Simon Riggs Discussion with: Josh Berkus, Jaime Casanova, Peter Eisentraut, David Fetter, Yeb Havinga, Alvaro Herrera, Petr Jelinek, Tom Lane, MauMau, Bruce Momjian, Jim Nasby, Michael Paquier, Fabrízio de Royes Mello, Neil Tiffin
Continue reading Waiting for 9.5 – Add pg_audit, an auditing extension