SharePoint 2010 Search Refinement Panel web part

In SharePoint 2007 - I have used "faceted search" from codeplex http://facetedsearch.codeplex.com/ to grouping search results by different category name, total number of values inside group, etc... BUT SharePoint 2010 provides OOB web part called "search refinement panel" in which we can achieve more or less same type of results and output like faceted search.

For achieving grouping functionalities in SharePoint 2010 search refinement panel web part - we can create managed property from central admin and can customize XML for search refinement web part to display search results by different categories.

Result type, site, author and modified date categories are by default in search refinement panel web part.

Here are some reference links for customizing refinement panel web part in SharePoint 2010:

http://searchingsharepoint.wordpress.com/2011/06/09/customizing-the-refinement-panel-for-sharepoint-2010-search/

http://microsoftsharepointandbeyond.blogspot.com/2011/04/sharepoint-2010-refinement-panel.html

http://vinaybhatia.blogspot.com/2010/11/add-custom-category-to-search.html

http://msdn.microsoft.com/en-us/library/ff625183.aspx