It's definitely 2-disc. I had a saleslady at Odyssey open one to check. But relented after seeing the 4:3 indication. The technical details at Amazon for both the full screen and widescreen R1 editions show an extensive array of special features:
DVD Features:
Available subtitles: English, Spanish, French
Available Audio Tracks: English (Dolby Digital 5.1), French (Dolby Digital 2.0 Stereo)
Commentary by director Martin Scorsese, editor Thelma Schoonmaker, and producer Michael Mann
Deleted scene: Howard Tells Ava About His Car Accident
A Life Without Limits: The Making of The Aviator
The Role of Howard Hughes in Aviation History
Modern Marvels: Howard Hughes, A Documentary by the History Channel
The Visual Effects of The Aviator
The Affliction of Howard Hughes: Obsessive Compulsive Disorder
The Age of Glamour: The Hair And Makeup of The Aviator
Costuming The Aviator: The Work of Sandy Powell
Constructing The Aviator: The Work of Dante Ferretti
An evening with Leonardo DiCaprio and Alan Alda
OCD Panel Discussion With Leonardo DiCaprio, Martin Scorsese, and Howard Hughes' Widow Terry Moore
Still Gallery
Scoring The Aviator: The Work Of Howard Shore
The Wainwright Family - Loudon, Rufus and Martha
Number of discs: 2