In reply to FredMead:
The exact line is shown here (line n°4)
http://www.summitpost.org/images/132228.jpg
and here (line n° 4 again)
http://www.summitpost.org/images/132227.jpg
and here (line 1, 1b and 1a are alternative starts)
http://www.summitpost.org/images/131567.jpg
The route is very hard, probably (in overall terms of seriousness and overall committment) the hardest on the wall and one of the hardest in the Alps. It's very technical and very sustained, and very, very long - 36 pitches if you're using a 60m. No single pitch goes below 70° of steepness, and entire sections are 85° and above. There one long A1 section that could possibly go free with hard dry tooling. No single pitch is hard as the crux of "No Siesta" (another super-route on the wall), but the "Gousseault", as it's normally named, is longer and more serious.
The big feature of the climb is the fact that the line (a very logical and elegant one) goes above three enormous "ramps" that are located in the nw face of the Cassin spur, above the Shroud. The rock is relatively good, but in some area rockfall is frequent. The route is very exposed, and retreat after some point basically impossible.
The route was "almost" opened in one of the most controversial and tragic winter climbs in the history of mountaineering. On 11 February 1971 Desmaison began the climb with a young partner, aspiring guide Serge Gousseault. They found the route much more demanding than initially assumed, and progress was, for the first few days, slow but continuous (there were no modern ice tools available back then, so most of the climbing was on aid). One of their ropes was cut by rockfall, and given the lenght and lack of material, it was apparent after some time that had no chance to return unless they summited. Around Feb 18th Gousseault developed gradual symptoms of exhaustion (he was almost certainly suffering for some kind of glicemia related disease he had not previously disclosed to Desmaison).
Desperate to find an exit, Desmaison first made an attempt for an escape route towards the Hirondelles, but ice conditions prevented this. He then literally started to haul an almost incoherent Gousseault on a rightward ascending traverse toward the "Tour Rouge" on the Cassin spur, the left again on a last ramp. 80 meters below the summit Gousseault collapsed and refused to continue. Desmaison - who was still able to continue - decided to stay.
A this point, when it was clear they should have been rescue, things became even more complicate. A weird triangular thug of war developed between Desmaison, his wife Simone (who was initianlly in radio contact with him), and the Rescue authorities at Chamonix. Basically, the thing was that back in 1966 Desmaison had been kicked out from the Chamonix Guides because of an "unauthorized" (and over publicized) rescue of two Germans on the Drus he had organized with people like Garry Hemmings and Mick Burke. In 1971 he was still in bad terms with the Company and generally speaking the Cham authorities. They could not wait to get asked to rescue him, while his wife was uneasy between asking formally for a rescue or (she had no evidence of Gousseault illness because of broken radio link) just wait. When a heli was sent to see what was happening, there was an exchange of signs that the pilot took for "all is OK", while Desmaison was signalling "we need rescue" (since then a formal set of signs has been formalized). Things got worse again when on the Courmayeur side the local guides started to make pressures to launch an indipendent rescue attempt, just to get a flat "no" from Desmaison's wife - (still unsure his husband needed help or not).
When finally she decided to ask formally for a rescue, (and we're now on Feb 22nd!) Gousseault had already died, and Desmaison was immobilized with an incoming kidney failure. More mishap and controversy followed and finally on the 24th, a military helicopter with one Cham guide and three from Courmayeur mandaged to land on the Walker summit and snatch Desmaison away when he was on his very last leg (I've pictures of the rescue and he looks completely done for good!)
The whole story was an enormous media event, with hourly coverage from TV and radio, special newscasts etc. A bitter controversy followed, with Desmaison accusing Chamonix major Herzog (the one of the Annapurna) of big mismanagement, and Herzog accusing Desmaison to have badly staged a publicity stunt that had gone wrong. It's interesting to know that one after effect of this was the constitution of the PGHM as a separate, full time rescue corp, indipendent from the Guide Company.
Two years later, again in February, Desmaison returned with his son in law Michel Claret and with Courmayeur guide Giorgio Bertone (an all round amazing climber) and completed the route, discovering, to his bitterness, that the last 80 meters where actually easier than he had originally thought, and so Gousseault could have lived. The repetition took 7 days
In August 1977 Gordon Smith and Tobin Sorenson (who was bent on repeating in fast style all the hard, unrepeated routes on the Alps) made the first repeat. They did it in three days or four days (details are unclear), using a lot of the material left here three years before. They almost certainly made an initial direct variant (it's shown on my pictures) and spoke of severe rockfall danger.
The route was left alone for many years (thanks also to very bad publicity and progessive lack on interest on mixed climbing, until February 2000, when French climbers Stephane Benoist and Patrice Glairon Rappaz made the third complete ascent, in five days, following the original route. They spared no superlatives on the route, describing it as one of the hardest and most beautiful they had ever done. They described Desmaison performance as "extraterrestrial", and published a detailed topo you can find here
http://www.tvmountain.com/images/actualite/marsigny03/topo.jpg
In October 2000 Patrick Berhault and Philippe Magnin made the fourth ascent, in a blinding 26 hours of actual climbing. For technical reason they however didn't follow the entire route, but started on the Linceul then traversed right to reach the original route at one third. Patrick made incredible pictures, available on his "La Grande Cordeè" video.
Then in March 2003 Chamonix guides Olivier Larios and Francois Marsigny did the fifth repeat, in four days. They again followed the Smith-Sorenson initial variant (that maximized ice climbing and speed). They impression of the route was absolutely extatic. Marsigny defined it one of the best he had ever done - and one of the hardest.
Two more attempt for a repetition have been apparently repelled in 2004.
Ok, hope this has been of help!