Both these test sites have the latest trunk install of Thematic and identical child themes. The difference being that at the first link the body class comes out as expected as generated by Thematic:
<body class="wordpress blogid-1 y2010 m09 d16 h21 singular slug-community-groups page pageid-25 page-author-perry page-parent page-comments-closed page-pings-closed loggedin windows firefox ff3">
while the other site has the following body class (the Wordpress default body classes I think):
<body class="home page page-id-58 page-template page-template-default logged-in class-name windows firefox ff3">
Everything else seems to be working as expected - I can probably work with this but it bothers me that it isn't working as it should be.
Any ideas anyone?