Recently I was asked to provide the same kind of "Current Site Navigation" on a Meeting Workspace template that appears on the site’s master page. Amazingly, given the right tools this is actually a VERY simple task. However, in order to accomplish this in the easiest method you will need SharePoint designer.

Steps:

1. Open the Site using SharePoint Designer
2. Open the Page with SharePoint Designer
3. On the Custom Content object in the Content Place Holder PlaceHolderLeftNavBar click on the > button and choose to revert to the master page content.
   1. If you want you can simple delete everything in the <asp:Content ContentPlaceHolderId="PlaceHolderLeftNavBar" …>…</asp:Content> section from the page
4. Save the page back to SharePoint
5. Go to the Site Navigation Settings page
   1. Site Actions->Site Settings
      
   2. Navigation (under the Look and Feel heading)
      
6. Choose the Display only the navigation items below the current site radio button in the Current Navigation page section.
7. Customize the Current Navigation items in the Navigation Editing and Sorting page section.