I've seen about 10 threads about people complaining that they want to see Master Chief make an appearance in Halo 3 : ODST. WHY? This makes no sense at all. Bungie wanted to try something new and incorporate someone other than MC.
If you guys want to see [and play as] the Master Chief go play Halo 1, 2, or 3! Or if you're so desperate, go print out a picture of him and hang him on the wall while you play Halo 3 : ODST.
*sigh.
[Edited on 08.08.2009 8:19 AM PDT]