OCLC announced that a new updated and more powerful version of their Duplicate Detection and Resolution Software has been completed in May. This new software is now being run in order to find duplicate records in WorldCat.
According to OCLC:
In May 2009, the new software was put into production following rigorous planning, development, and testing. In addition to its ability to deal with continuing resources, scores, sound recordings, visual materials, maps, and electronic resources, as well as books, this new DDR is much more sophisticated than its predecessor in its power to distinguish legitimate matches from incorrect ones. It also has the flexibility to allow selection of certain categories of bibliographic records to target for deduplication. Processing of small subsets of WorldCat against the live database has begun. A full pass through the WorldCat database will begin later in 2009.
Having the new DDR software in production will result in the merging of a larger number of bibliographic records. Regular removal of duplicates will provide a better WorldCat for all its users.
Hopeful this new software will help to clean up the database and rid it of numerous duplicate records.
The complete news announcement: http://www.oclc.org/news/announcements/announcement369.htm