The DVD and Blu-ray boxset of Season 1 have been confirmed. March is the US date.
Extras -
Both the DVD and Blu-ray versions include the first season’s 10 episodes, plus (descriptions are the official text):
Complete Guide to Westeros
“An interactive compendium of the noble houses and lands featured in season one.”
Making Game of Thrones
“An exclusive 30-minute feature including never-before-seen footage from the set and interviews from the cast and crew.”
Character Profiles
“Profiles of 15 major characters as described by the actors portraying them.”
Creating the Show Open
“An inside look at the creation of the Emmy-winning opening title sequence for Game of Thrones.”
From the Book to the Screen
“Executive producers David Benioff & D.B. Weiss, and author George R.R. Martin talk about the challenges of bringing Martin’s epic fantasy novel to life on HBO.”
The Night’s Watch
“An in-depth look at the unique order of men who patrol and protect the Wall, a 700 foot ice structure that separates the Seven Kingdoms from the darkness beyond.”
Creating the Dothraki Language
“An insightful glance into the comprehensive language created for the Dothraki people in Game of Thrones.”
Audio Commentaries
“Seven audio commentaries with Cast and Crew including David Benioff, D.B. Weiss, George R.R. Martin, Emilia Clarke, Peter Dinklage, Kit Harington, and more.”
http://insidetv.ew.com/2011/11/30/game-of-thrones-dvd/