From their site:
"MyHeritage.com Research is a search engine built specifically for genealogy, capable of searching hundreds of major genealogy databases in a single query. It's the most comprehensive genealogy research tool existent today and the first of its kind. In simple terms, this search engine runs each query simultaneously in hundreds of genealogy databases, aggregates the results and displays them in one consolidated report. This gives you more genealogy search power than has ever been available before, in a simple, friendly and convenient interface."
For more on this or to use the feature, visit their pages at: MyHeritage Genealogy.