User blog comment:DaNASCAT/Technical Update: March 22, 2011/@comment-1393830-20110322213659/@comment-1656630-20110322225002

Oh, actually, this needs clarification: the bug we're pushing to fix is that the subject/headline bar on new talk page sections appears *below* the edit field, when it should appear above. This functionality repurposes the summary field, so it's unlikely that you're going to see both fields at the same time, no matter what.