SP 2007 does not support CAML joins between list; however, SP 2010 has added the ability to do CAML joins but with certain restrictions:
http://msdn.microsoft.com/en-us/library/ee539975(office.14).aspx"
Currently, qListView can not be used with a Linked Data Source. Technically, you can paste in CAML assuming it is formatted correctly, but that won’t help with the display of fields. Since SP 2010 support CAML joins, we will look into this feature for future version of Quest Web Parts. In the mean time, I found a couple of 3rd Party web party products that might help you now:
http://sharepoint.wice-group.com/en/joinpro/overview.aspx
Another approach would be to use SQL Reporting Services and a 3rd Party addon to extract and display list data:
http://www.enesyssoftware.com/language/en-US/Products/EnesysRSDataExtension/Overview.aspx
Both of the approaches above work with SP 2007 and WSS 3.0 and above.
Joining list using CAML is a powerful new SP 2010 feature and we will look into this capability for future versions of QWP.
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