For anyone thinking of heading to the Verdon this Autumn, the Sentier Martel is going to be closed for restoration work between September 5th and December 31st 2011. This will mean it will not be possible to walk in to the bottom-top routes like La Demande and ULA, though of course you could abseil in from the top.
Details here: http://www.alpes-haute-provence.com/randonnee-verdon/fermeture-sentier-blan...
Translation of the key info:
The trail is open until Sunday, September 4 inclusive.
The trail will be closed to the public from Monday, September 5, 2011 to December 31, 2011.
(the area of ​​the Couloir Samson, until Trescaïre viewpoint, will be open until Monday, September 12, 2011)
The entire trail will be open to the public from January to September 2012
Work will begin early September and end mid December.
The central part of the route (Brèche Imbert) will be closed to the public.
The upstream and downstream sectors will remain open to the public during the construction period.