There's always been an object 0 actually - the security context root. There can never be a *package* or any other normal object there, though.
However the security context root is now at -4 and object 0 is the new "unregistered visitor" party I created in order to help speed permissions (gets rid of the UNION clause to return 0 in permissions views)
This is only in the PG version at the moment, I'm about 1/2 way through the changes for Oracle but haven't committed any.
Anyway ... Bruno's problem is the notifications package not being mounted though, as you mention ...
