Version 0.95 of the Alfresco PDF Toolkit has been released, sporting a major change to the PDF watermarking feature.  Previously, as referenced here, PDF text watermarks were applied using a simple "tag substitution" to include bits of metadata in the watermark.  This release removes the old "tagging" mechanism and adds support for FreeMarker markup in the watermark text instead.  The text watermarks are already much more functional than they were, supporting a subset of the default model specified in the Alfresco Template Guide.  The default model specifies the objects that are available to FreeMarker templates in the repository.  I intend to add support for most of the default model that might be useful to include on a watermark.  So far the following root objects are in the model.

userhome - current user's Home Space template node

person - Node representing the current user's Person object

space - The current space template node

document - the current document template node

date - a java.util.Date object representing today's date

Using FreeMarker markup in a PDF watermark is simple, just like using it in any other template in Alfresco.  When configuring the action in a content rule, just paste the FreeMarker markup into the "Watermark Text" field.  When the rule is run, the template is processed and the resulting text is applied to the PDF document as a watermark.  Easy, right?  For example, if you want to mark the PDF document with the username of the person that uploaded the document, just put the following in the Watermark Text field:

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Document Added By
${person.properties.userName}

Or, if you would rather have the user's first and last names, you could use the following markup:

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Document Added By
${person.properties.firstName} ${person.properties.lastName}

These are obviously simple examples, but they make the point.  If anybody out there has any other suggestions about what should be in the FreeMarker model for PDF watermark text, please send it along and I'll do what I can.