When we started to develop Plugems we had multiple applications that all shared a similar look and feel. One concept that emerged recently for me was that layouts can act like objects. In our suite of applications, we have a base layout that each application can derive from to satisfy it's unique set of presentation requirements. For example our UI plugem has the following:
Using a little magic from fora.pragprog we can extend our default layout writing the following:
<% inside_layout 'default' do -%>
<%= @content_for_layout %>
<% end -%>
Plugems enables you to share common UI widgets across multiple applications. Common assets (css, js, images) can live in a plugem, but be shared across applications at deployment time. I hope to post more in depth on this topic in near future.