A special case of this is HeadlineSyndication.
Two relevant communications protocols are RichSiteSummary and ResourceDescriptionFramework. Specific to wikis, there is also the RSS extension module ModWiki, which allows for UnifiedRecentChanges.
See OpenWiki:RDFSiteSummary for a description of how OpenWiki pages can transclude RichSiteSummary feeds from other sites. OpenWiki:ScriptingNews mentions that the transformation from RSS to HTML was done entirely through XSLT.