On July 27th we went live with faceted search and relevance ranking based on both OCR and MARC metadata in Full-Text Search in HathiTrust. These are the top two features identified by the HathiTrust Full-Text Search Working Group.
The relevance ranking now will give volumes that match a user's query terms in both the OCR and in the title or author or subject a higher ranking than a match in only the OCR. There is much more work to be done in tuning relevance ranking, but this is a first step. Search results can now be refined by selecting facets such as subject, date or author. Although selecting facets can help users drill down to narrow large result sets, using very specific terms and especially using phrases in quotes remain one of the best ways to get reasonably small result sets. Over the next few months we will be releasing further improvements in ranking and more of the features identified by the task force.