Some people think Halo 3: ODST is a very underrated entry in the Xbox 360's signature franchise. But, based on the image above (which has been lightened to be viewed more easily), one of the last Halo games that Bungie worked on might have been important for other reasons. Could they have been teasing Destiny three years ago? Well, there's the one inhabited planet with the smaller white globe, just like in the Destiny image from the leaked document. Sure seems like it was staring us right in the face, guys.
(Thanks, tipster Christopher!)
Update: As noted in comments below, a Halo level artist seems to confirm that the sign in ODST was in fact a teaser for Destiny