We have done a bunch of work on search in london (eg. added subsite scoped search which is in openacs now) and fixed a bunch of bugs in the existing indexer so it's more robust. We also added the RSS bit (though not for search results specifically but generation of syndication records when indexing). We are also integrating with external classifiers and external search.
We did the /o/OBJECT_ID interface which is in acs-subsite already (although we use this more for category browsing).
nothing on oracle though and nothing for dotlrn.