It is my understanding that the side air bags are on the front seats only. At the Hondsnews web site it states
"The front passenger's side airbag has an automatic cutoff system that is designed to prevent side airbag deployment if a child (or small statured adult) leans into the side airbag deployment path. Once the child returns to an upright position, the side airbag will be able to deploy and provide protection in the event of a side impact."
Honda's are most likely just in the front. Curtain side airbag systems do extend to the rear, but I do not think Honda has this type in the Odyssey. You may also be interested in this thread on side airbags and kids in carseats:
thanks for the most informative info, Caviller! I will probably be the first to say this on this site, but I think I'm glad I now own a '01 and am not waiting for '02. Most often I have a 9 yr old in the rear, a near 5 yr old in a booster w/ reg. seatbelt (latched) in the rear, and two rear-facing infants in the middle. I don't think I need/want side airbags. SO often both my girls are asleep in the back, leaning against the side, and I would be worrying about the safety of sensors, are they working, etc. By the time I buy my next Odyssey, there will be (I hope) 10 more years of research on their safety.
Just to re-iterate, I do not believe the Odyssey has any type of side airbag for any of the rear seating. In addition, the federal letter to carmakers requires them to deactivate rear seat side airbag systems at the factory unless they can attest that they do not cause risk to child passengers. The dealer can then re-activate them for those requesting it.