When you use the top level (Gloda ?) Search and get the summaries, but click on "Open email as list", it always uses a default (not particularly helpful) column layout, and doesn't remember if you change it. (e.g. to add Location, or switch From to use Correspondant (from the SHowInOut extension) both of which are often relevant when you are searching). This is similar to bug #660211 but that is marked as Fixed, so I believe I'm supposed to file this as a New bug.