In reply to dan tipper:
Depends where exactly you are going in the Ecrins and what sort of stuff you're looking to do...
The Oisans Est book covers only the Eastern areas I think. And it's all in French.
For the bolted stuff around Aielfroide there's a guidebook available in the village.
Same for the stuff around La Berade
For bigger routes in the mountains try the Oisans (2 volumes - E&W) books if you can read French.
Also, there is a guide to some of the sport climbing called "Grimper dans le Haut Val de Durance" or something along those lines. Covers some of the stuff in Ailefroide, plus Mont Dauphin and Ponteil etc.
You might need a few different guides to cover all eventualities. They are all available locally in Argentiere La Besse, Ailefroide etc.