I was browsing Dave Wilton's "Wordorigins Org" EZboard forum and discovered this in his glossary:

"Mantle:" A reference to a 'mantle of invisibility,' a term used on this board for someone whose post is ignored by a later poster and the same facts/comments repeated as if the original poster were invisible.

IMNSHO, this beats "chopped liver" into a fine grade of paté, and I think we should filch.. er.. adopt it.