In reply to ROB W:
I went for an attempt on the Forbes Arete 3 weeks ago and took the guidebook approach due south from below Pte. 3238. It took us through a crevassed maze of hell and we both punched through weak snow bridges, it wasn't a nice place to be. After the initial snow slopes up to La Bosse on the Chardonnet we decided to bail with an enormous crevasse on the hanging glacier that had a single bridge across and no obvious way round.
On all the descriptions, pictures and other peoples reports there is no mention of an enormous crevasse up there so I think it could be quite new with the poor winter and hot summer.