In a SharePoint 2010 Enterprise Wiki I was unable to select any Categories; the Categories field was greyed out and the Browse button just didn’t work.
Opening the Library Settings, and selecting the Wiki Categories column I was presented with the error message: “The required feature is not enabled for this column type”.
Hide the Quick Lauch Bar etc. in SharePoint 2010 Team Sites Welcome Page and other Wiki-pages
In SharePoint 2010 you can use the Content Editor Web Part as was the case in SharePoint 2007.
However, the div-tag has changed and you will also have to set the correct left-margin to another div-tag to avoid having a whitespace where the Quick Launch Bar was placed.