The second disc -- exclusive to the Legendary edition -- includes cinematic material from the first two Halo titles, including developer commentary. Also on the disc is special content from the makers of Red Vs. Blue and This Spartan Life. Finally, the Legendary edition will include exclusive storyboard art featuring important moments in the Halo storyline.
The Limited ediiton will cost $69.99 and comes in a spiffy metal case. It includes the same behind the scenes DVD as the Legendary edition and a Halo fiction and art book. The art book contains info on the various species in the Halo universe and reveals new info that expands on Halo's storyline. Just so Limited edition folks won't feel jilted -- and to give Legendary purchasers a reason to buy another edition -- the art book is exclusive to the Limited edition.
Finally, the plain ol' regular edition contains nothin' but Halo 3 for the price of $59.99.
So, now that all has been revealed, which edition will you be bagging come