FreeMarker template code to create a list of users sorted by their last blog post publish date across many blogs or a single blog in Jive SBS. Tested on version 4.5.5.2 in the blog-macros.ftl file.

getBlogContributors.ftl

<#function getBlogContributors blogs>
  <#local contributors = [ ]>
  <#local contributorsWithDate = [ ]>
  <#local blogPostObjectType = 38>
  <#local resultFilter = action.getResultFilter()>
  <#if blogs?has_content>
    <#list blogs as blog>
      <#list blog.contributors as contributor>
        <#if (!(contributors?seq_contains(contributor)))>
          <#--  check if user is blocked -->
          <#if (! (contributor.properties.containsKey("visible.blog.contributor") && (contributor.properties.get("visible.blog.contributor") == "false")))>
            <#-- add property with last blog post publish date -->
            <#local lastBlogPostPublishDate = contributor.creationDate>
            <#-- repurpose the result filter -->
            ${resultFilter.setUserID(contributor.getID())}
            ${resultFilter.setNumResults(1)}
            ${resultFilter.setSortPropertyName("PublishDate")}
            <#-- limit search if there is only one blog in list -->
            <#if blogs?size lte 1>
              ${resultFilter.setBlogID(blog.ID)}
            </#if>
            <#local lastBlogPosts = jiveContext.blogManager.getBlogPosts(resultFilter)>
            <#if lastBlogPosts?? && lastBlogPosts.hasNext()>
              <#list lastBlogPosts as lastBlogPost>
                <#local lastBlogPostPublishDate = lastBlogPost.publishDate>
              </#list>
            </#if>
            <#local contributors = contributors + [ contributor ]>
            <#local contributorsWithDate = contributorsWithDate + [ {"user": contributor, "lastBlogPostPublishDate": lastBlogPostPublishDate } ]>
          </#if>
        </#if>
      </#list>
    </#list>
  </#if>
  <#return contributorsWithDate>
</#function>

<#if blogs??>
  <#local contributors = getBlogContributors(blogs)>
<#else>
  <#if blog??>
    <#local contributors = getBlogContributors([blog])>
  </#if>
</#if>

<#if contributors?? && contributors?size gt 0>
  <ul>
    <#list contributors?sort_by("lastBlogPostPublishDate")?reverse as contributor>
      <li>${contributor.user.username}</li>
    </#list>
  </ul>
</#if>