Does the ListView in Whidbey support a display like a threaded conversation, much like Outlook Express does in its news reader? I understand the Listview in Win32 can but has this been exposed in managed code yet?

The ListView has a NumIndents property that provides the ability to make some rows look more "indented" than others. You'll want to perform custom painting (which was added in Whidbey) to paint the "+/-" image, and you'll have to insert and remove list view items when a row is expanded and collapsed.