WCF Web Service in SharePoint 2010

Here are very good links about how to create custom WCF services in SharePoint 2010:

http://answers.oreilly.com/topic/1404-how-to-customize-wcf-services-in-sharepoint-2010/

http://blog.sharepointbits.com/2010/04/custom-wcf-services-in-sharepoint-2010_17.html