At the end of Halo Reach, one of the last cutscene is inside Pillar of Autumn's cargo hold, and tilting the camera reveals Master Chief in cryo, ready to start Halo CE
Yes, the location of where he actually wask up at the beginning of Halo CE isn't exactly where the camera is at the moment, and this is more of easter egg that players need to figure out, but I think it was very cool and impressive for Bungie to have it in there.
Now only if 343i (oh i'm sorry; "Halo" studio), is half as dedicated as Bungie used to be..... Which the same can be said about current state of Bungie