We've updated our Blogger site to use the same layout/style as our core site. Surprisingly easy! There are some great resources just a click away when editing the layout (Layout tab) that show what data name space elements are available and how they work. Importing style was brain-dead easy. Final step is to tune the layout for some of the Blogger specific elements in use on all the pages for email-links, track-back, post-comment and others. Quick trip through the page with Firebug and it's done.