Is there anything that must be done to make db2 databases 64bit after running db2iupdt -w 64 to update the instance to 64bit ? I'm on db2 v8.2 Fixpack 9, and Solaris OS.

Thanks

no db2iupdt is enough
just verify the .profile if any setting specific to lib32
lib is default and in your case 64b

Would I have to rebind packages?

I think its necessary to rebind everything

On AIX, we had to chage the data and stack settings of instance id, data to unlimited, stack to 32768. It may help to find out what the values should be for your platform.
You may need to make some configuration changes since the pointers become larger. We noticed that the number of deadlocks increased. There were some other config changes which we made, however, we did add memory to the servers. We increased FCM parms, sortheap, doubled buffpage, dbheap.

HTH