I'm resisting the urge to be snarky... I understand that this has toasted their ability to speak to tech-saavy people off-the-record, but I don't expect them to lose any advertising over it. As far as credibility, since when have we required that from our news media? I always just pick the outlet that best fits my confirmation bias.
The phone "hacks" were on lovable, empathetic characters: Hugh Grant, the royals, soldiers, little girls. Bradley Manning, on the other hand, has been suffering a character assassination from day one. You lose advertising by going against public opinion, not necessarily from just being bastards.