This from the OTN blog post by Justin Kestelyn: "official Oracle Documentation is being indexed by Google as we speak."
Also, there is an Oracle DBA Toolbar for IE available.
There is also a custom OTN button available for the Google Toolbar (IE only :-)
Finally, check the OTN Semantic Web at http://otnsemanticweb.oracle.com/, that was announced last month on the OTN blog here.