A bunch of users will be moving to a diff organization in my comp. They have requested to setup an auto-forward - I know how to do this. But they would also like to do an autoreply that tells others that they have moved to a new org. Is it possible to do both? Would i just setup an "out-of-office" reply for them using OWA?

It would be better if you did this on the gateway so you can manage situations such as email loops which can occur. However, you can do setup the forwards on the user object in AD itself and configure a auto-reply using a rule using Outlook, this will apply to every message the mailbox receive. Create a rule with no condition when doing this. Out of office rply will only work once for a user, not for every message sent by the same user. Sukh

I would recommend that you not do this. This can lead to mail loops and auto-replies to spoofed senders.