Infopath and Webservice reference

http://blogs.msdn.com/jannemattila/archive/2007/01/21/infopath-and-web-service-data-connection.aspx
http://blogs.msdn.com/philoj/archive/2005/11/08/490200.aspx

http://msdn.microsoft.com/en-us/library/aa192516(office.11).aspx