Create your CQWP (Content Query Webpart) rolling up whatever you’re planning on rolling up, and then export it to your desktop. Edit it in notepad++, textwrangler, whatever texteditor you use.
Find the “ViewFieldsOverride” property and replace it with the following:
<property name="ViewFieldsOverride" type="string"><![CDATA[<ProjectProperty Name="Title" />]]></property>
Save the file as “sitename.WebPart” and import it into your page, insert into a webpart zone, and you are ready to style the XSL.
In your ItemStyle.xsl template declare the following:
<xsl:value-of select="@ProjectProperty.Title" />
Go back in and edit the webpart…you should see that now there is a field called “ProjectProperty.Title”, leave it blank, it’ll take care of itself.
Thanks to this site for most of the solution.