From that message:
"The only key feature that distinguished RedLightGreen from WorldCat.org was citation formatting, and the WorldCat.org development team quickly acknowledged that this feature would be a useful addition to WorldCat.org and are working quickly to make this feature available. Below is an overview of RedLightGreen features, and how they are covered in WorldCat.org.
- FRBRization of results: RedLightGreen uses a FRBR-like approach to group works in RedLightGreen. OCLC is already employing a similar FRBR-like approach in Open WorldCat. Grouping of works is slightly different than in RedLightGreen; for example, titles in different languages are treated as separate works.
- Ranking: RedLightGreen orders results by a combination of relevancy to search term and how widely held a work is among contributors to the RLG Union Catalog. Open WorldCat uses a similar approach, weighting the terms in certain fields and the currency of a work, along with how many holdings a work has.
- Faceted display: RedLightGreen offers users facets for narrowing search results for subject, author, and language. WorldCat.org also offers facets as a way of narrowing a result set; currently facets include author, content, format, language, and year.
- Citation formatting: RedLightGreen offers a very popular bibliographic citation feature. OCLC plans to offer citation formatting based on the RedLightGreen feature -- you can look for this in early 2007."