I have finally been able to map a domain to my typepad account. In practice it means that my site can now be reached at www.jasonclark.ws. The .ws is the western samoa top level domain, but increasingly people are using it as short hand for 'web site'. Most other jasonclark domains were already registered, so I plumped for the .ws.
This link also includes a full RSS feed from the domain.
BTW if you want to register a domain and map it to your typepad account, pair.nic are cheap, and offer free custom DNS (what you need to get your domain properly linked to typepad).
So please update your bookmarks, RSS feeds, and let others now if you feel inclined, thanks.