A quick note to let you know we have recently updated the tutorial for mapping a domain to your TypePad blog. You can get the new tutorial here.
Not sure why you should map your domain?
When you set up your blog on TypePad, the URL for your blog includes TypePad's domain: www.yourblog.typepad.com
For example, the underlying domain for this blog is nextlevelpartner.typepad.com/babb but the domain you see, that's mapped over the TypePad domain is www.buildabetterblog.com. Which is better? :-)
Rather than promote TypePad, you really need to brand you, your company, your book...whatever your blog is about. You need to register a domain and then map it OVER the TypePad domain so you are promoting YOUR business and establishing your online brand.