You can create your own Navigation Provider, similarly to the way shown in the linked article. The reason that that solution won't work on foundation is that he's chosen to base his on the 'PortalSiteMapProvider' class, which is only available in SharePoint Standard/Enterprise, but you could write your own, as a child of the SiteMapProvider class. SharePoint does use quite a number of different navigation providers; you can see some of these if you look within the web.config for one of your web applications.
You would also probably have to write a new Navigation Control - thing to consume and render the bits of the sitemap that you want - if you're goign to want fancy text and icons. You will then need to figure out how you're going to put this control into your page - either as content overriding the default content of the masterpage, or perhaps as a new masterpage itself.
It's worth noting that the Navigation API - the idea of SiteMapProviders and controls that consume them - is a standard part of ASP, so there are plenty of 'non-sharepoint' examples out there too.
This approach does take a while to get your head around, but once you understand the navigation API, it's pretty straightforward. I'd say it was the right approach, though there are others.