MTV Multiplayer asked Bungie's Brian Jarrard whether the Master Chief would be making an appearnce in Halo ODST. The answer: No. Duh. ODST takes place on Earth in between the events of Halo 2 and 3. The Chief is off on another Halo in some distant galaxy during this time so obviously he won't be appearing in the upcoming sidestory.
If you are wanting some more Master Chief in your life, then you'll just have to wait for Halo Reach. The Chief, or a bunch of other SPARTAN IIs, should have a starring role in Reach. Seriously, go buy the first Halo book. It's really good.