Zena has a basic tagging facility now:

Simply type a list of comma separated values in the tags field on the edit popup.

API

Tags can be added by defining the “tag” pseudo attribute:

node.update_attributes(:tag => 'foo') # add "foo" to tags
node.update_attributes(:tag_list => 'bar, foo') # define tag list

pseudo sql

You can use tags in queries. Simply use the pseudo attribute ‘tag’:

images where tag = "family" in site

Or (using a query parameter):

images where tag = param:t in site

zafu

To list the tags:

<r:tags><r:each join=', ' do='[name]'/></r:tags>

To create a list of tag links (notice how the t attribute is dynamically set to the tag name) :

<r:tags do='each' join=', ' do='link' href='root' t='[name]'/>

If you want a pretty ajax field with delete buttons on the tags:

<r:form update='tags' done='$("node_tag").clear()'>
  <r:input id='node_tag' name='tag'/>
</r:form>
<div id='tags' do='block' do='tags'>
  <span do='each' join=', '>
    <r:show attr='name'/><r:unlink/>
  </span>
</div>

This is just the beginning of tags. Tag cloud, improved search and other helpers will come later.

PS: Tags are implemented as “comments” on anonymous links. This means that you can use the “l_status” information to scope tags.