Maryanne has been plucking away in Icecrown Citadel defeating The Lich King and other encounters with some of her guildmates, friends, regulars and randoms. All the raiding amounted up to a certain quest involving a shiny weapon.
Just to add, don’t be worried about Maryanne’s soul. It is Shadowmourne and not Frostmourne she obtained. However I am sure it was tempting to wield it.