We are using the Content Search WebPart on a page in a publishing site to show items that are in another site collection. If a person searches the site the CSWP is on they do not get any results that are part of the CSWP. It seems counter intuitive that you have to go to the other site collection to search. Is there any way to make this work?
In the search settings section for the site collection you need to select "Enable custom scopes (such as "All Sites") by connecting this site collection with the following Search". Then use only contextual scopes (such as "This Site").
SP 2013: Chris O'Brien has posted article about this: http://www.sharepointnutsandbolts.com/2012/10/using-content-search-web-part-and.html