The type or namespace name 'Publishing' does not exist in the namespace 'Microsoft.SharePoint' (are you missing an assembly reference

This error crops up if you try to use publishing assembly reference in your SharePoint 2010 projects using Visual Studio 2010.

To resolve you have to do few steps mainly adding reference to System.Web.DataVisualization.dll .
Perform all steps listed in this link and you should be good:

http://social.technet.microsoft.com/Forums/en/sharepoint2010programming/thread/586e3c4e-5936-42f5-9752-e6ac8c92d4c0