The blog is sticking with one of Movabletype's default formats for the time being, because comments and registration is working - we think.
It would be good if a few of you could try leaving a test comment, so that we know everytrhing's OK. Once sure of that, the blog will start to look like the rest of the site again, and indeed, in line with a previous announcement, gradually take over from the main page as the route into the site.
Working for me now, Michael!