In reply to Merlin:
I'm not out there so can't help you first hand, but from what I've been reading, there's a fair few big holes still open. But some guides set a track down the Grand Envers last week and it looked serious!
Take a look at the Chamonix webcams and have a look at this link:
http://www.fondation-eng.org/station_meteo.php?lg=fr
It's a webcam from the Requin hut showing the section down the Geant Seracs.
Sorry i can't be of any proper help