Streams clearly looks like a strategic direction for Oracle. Some of the enhancements in this release (particularly, I think, the changes regarding supplemental logging) promise to make the logical standby database a viable option in the near future.
A new procedure, dbms_repcat.streams_migration, is available to assist in migrating from Advanced Replication to Streams.
A new package called dbms_streams_messaging is available to ease the process of enqueueing and dequeueing messages from a sys.AnyData queue.
Prior to its release, there were some rumors floating around about Oracle Database 10g. One of these was that the SQL*Plus client would be done away with. I'm happy to report that the rumors of the demise of SQL*Plus were premature and that it is very much alive and well. In fact, some enhancements are present in SQL*Plus in Oracle Database 10g:
Enhancements to the describe command
Enhancements to the spool command
Changes to behavior of the SQL*Plus profile files
New define variables
The ability to do variable substitution at the SQL prompt
The new SQL*Plus compatibility command
Support for whitespace in filenames and paths
If you use rules in the database, you will want to know that the SQL*Plus describe command is now enhanced to describe rules, rule sets, and rule evaluation contexts. Thus, you can quickly look up rule specifications, rather than having to reference the data dictionary views themselves.