The original Marvel Phase One box set was delayed due to a lawsuit over the packaging it was to be shipped in. Now it looks like the set will be ready for release in it's new case on April 2 (via EW).
EW has also learned that the set will include some teases for the upcoming Marvel Phase Two. Marvel Studios producer Kevin Feige said it will include "footage, concept art, and a few new surprises" from Phase Two. Phase Two of Marvel's cinematic universe includes Iron Man 3, Thor: The Dark World, Captain America: The Winter Soldier, Guardians of the Galaxy, and The Avengers 2. "Also, look for a nod to Iron Man 3 in the Tony Stark S.H.I.E.L.D. file in the box set," teased Feige.
The box set will also include deleted scenes not found on previous Blu-ray releases, like the alternate ending to Thor (which you can see over at EW). "We went back to the editor's assembly of each film and discovered some rare moments that dropped out of the films early on and had not been released on prior discs," said Feige.
The Phase One box set will include ten discs featuring six movies, Iron Man, The Incredible Hulk, Iron Man 2, Captain America: The First Avenger, Thor, and Marvel's The Avengers. The set will now be enclosed in a new case but will still feature the 'working' Tesseract cube and S.H.I.E.L.D. files on most of the characters.