For Reader X, sticky notes and highlighter type of annotations are by default available and can be added on any pdf unless that pdf is secured (or has some special permissions due to which commenting has been disabled.). If you wish to enable all the types of annotations then you need to do the following. Open the pdf in Acrobat (any version). Click Save As->Reader Extended Pdf->Enable Commenting and Measuring.
Hope that helps.
Europe, Middle East and Africa