As I am thinking more about support for this functionality, all it would really need to support is the ability to re-use the "divleft", "divcenter" and "divright" as CSS classes as opposed to IDs.  If they were implemented as classes, in theory you could have something like this:

<div class="divcenter" id="MyCustomHeader"></div>
<div id="divleft"></div>
<div id="divcenter"></div>
<div id="divright"></div>
<div class="divcenter" id="MyCustomFooter"></div>

This way, you can have separately customizable page-specific headers and footers without affecting other portions of the layout.

To make the code cleaner, you may even just create a new css class that describes what it does, maybe something like class="full_width" or something.
 

Sounds great Joe.  This type of functionality is implemented in DotNetNuke.  I'm not sure how much you know about the skinning engine of DNN, but this example hopefully will help illustrate to you how you could possibly implement this feature. 

Basically, instead of using ASP.NET Panels with ids of "divleft", "divcenter", etc., DNN allows you to specify multiple content panes using block level elements, such as div with simply an id of whatever you want to name them.  Here's some example code to give you an idea:

<div class="toppane" id="TopPane" runat="server"></div>
<div class="leftpane" id="LeftPane" runat="server"></div>
<div class="contentpane" id="ContentPane" runat="server"></div>
<div class="rightpane" id="RightPane" runat="server"></div>
<div class="bottompane" id="BottomPane" runat="server"></div>

And then the css might look like:

.toppane { width: 100%; }
.leftpane { width: 28%; float: left;}
.contentpane { width: 40% float: left; }
.rightpane { width: 28%; float: right; }
.bottompane { width: 100%; }

Notice that there is a class and id definition, so that allows for unique identification of divs as well as the sharing of common style definitions using classes.  It seems that you have hard coded the values "divleft", "divcenter", and "divright" into the source code so that a skinner is forced to use this naming convention when designing the skin, but it seems that you could make it even more flexible using this method. 

I guess my question to you is can you add the bolded code into the skin and still be able to inject dynamic content from the CMS? (this code is from the techmania skin)

<div id="wrapcenter">
   <div runat="server" class="center-nomargins" id="topPane"></div>
   <asp:Panel id="divLeft" runat="server" cssclass="leftside" visible="True" SkinID="pnlPlain">
      <portal:PageMenu id="PageMenu1" runat="server" UseTreeView="true" TreeViewShowExpandCollapse="true" />
      <a id="startcontent"></a>
      <asp:contentplaceholder ID="leftContent" runat="server"></asp:contentplaceholder>
   </asp:Panel>
   <asp:Panel id="divCenter" runat="server" visible="True" cssclass="center-rightandleftmargins" SkinID="pnlPlain">
      <portal:Breadcrumbs id="Breadcrumbs" runat="server"></portal:Breadcrumbs>
      <portal:ChildPageMenu id="ChildPageMenu" runat="server" CssClass="txtnormal"></portal:ChildPageMenu>
      <asp:ContentPlaceHolder ID="mainContent" runat="server"></asp:ContentPlaceHolder>
   </asp:Panel>
   <asp:Panel id="divRight" runat="server" visible="True" cssclass="rightside" SkinID="pnlPlain">
      <asp:contentplaceholder ID="rightContent" runat="server"></asp:contentplaceholder>
   </asp:Panel>
   <div runat="server" class="center-nomargins" id="bottomPane"></div>
</div>

Hope this makes sense to you and gives you an idea of how to learn from DNN,

Erik