Identity Manager 12.5 or 12.6 installs Oracle 10g JDBC driver. All still works with Oracle 11g or 11gR2 databases.
You could see the log trace below that is indicative that Identity Manager is coming out of the box with Oracle 10g JDBC driver and will deploy that driver into WebSphere 7.x. This should not worry you since that driver is compatible with Oracle databases 11g or 11gR2 and so all is working well:
12/19/12 8:41:48:780 EST] 00000017 InternalOracl I DSRA8212I: DataStoreHelper name is: com.ibm.websphere.rsadapter.Oracle10gDataStoreHelper. [12/19/12 8:41:48:783 EST] 00000017 WSRdbDataSour I DSRA8208I: JDBC driver type : "" [12/19/12 8:41:55:955 EST] 00000017 SystemOut O 08:41:55,955 WARN [ims.tmt.CreateDatabaseSchema] ****** Schema for: Auditing is up to date. [12/19/12 8:41:56:120 EST] 00000017 InternalGener I DSRA8203I: Database product name : Oracle [12/19/12 8:41:56:123 EST] 00000017 InternalGener I DSRA8204I: Database product version : Oracle Database 11g Release 22.214.171.124.0 - Production [12/19/12 8:41:56:124 EST] 00000017 InternalGener I DSRA8205I: JDBC driver name : Oracle JDBC driver [12/19/12 8:41:56:126 EST] 00000017 InternalGener I DSRA8206I: JDBC driver version : 10.2.0.3.0 [12/19/12 8:41:56:128 EST] 00000017 InternalOracl W DSRA7042W: Oracle does not support the use of version 10 of their JDBC driver with the version of the Java runtime enviro nment that is used by the application server.