You can use the counter attribute of the list widget, like this:
<$list filter="
[tag[Background]tag{!!title}] +[sort[]]" counter="myCounter">
<h2><$link><$view field="title"/></$link></h2>
<$transclude mode="block" field="text"/>
<$list filter={{{ [<myCounter-last>!match[yes]] }}}><hr/></$list>
</$list>