check my esri forum thread replay: http://forums.arcgis.com/threads/60398-ArcSDE-execute-privilege-be-removed-from-public-on-Oracle-packages?p=329097#post329097
be careful in the order of executing the steps.
granting the following packages to “PUBLIC” role is always a security issue:
dbms_pipe
dbms_lock
dbms_lob
dbms_utility
dbms_sql
utl_raw
Geodata Master 