While both of those answers above work (well the example that tony links to anyway) I ended up finding the most succinct answer in that above post (comment by Kornelis Sietsma)
I guess render :layout
does exactly what I was looking for:
# Some View
<%= render :layout => '/shared/panel', :locals => {:title => 'some title'} do %>
<p>Here is some content</p>
<% end %>
combined with:
# /shared/_panel.html.erb
<div class="v-panel">
<div class="v-panel-tr"></div>
<h3><%= title -%></h3>
<div class="v-panel-c">
<%= yield %>
</div>
</div>