WordPress Search Results

Hello,
I am currently looking at creating a custom search results page and was interested in finding out what method, script, or plugin the wordpress.org plugin search is using for their results page. It seems to have everything I need sort by relevancy, highest rated, etc. It also pulls in author info. I also want to be able to set a priority or rating system to specific posts/pages that I want above other search results listings. Any info would be greatly appreciated.

Thanks in advance.