In reply to dgbryan:
I would also be keen to find out the answer to this. camptocamp.org website has quite a few ascents logged, and in fact for certain climbs (e.g. north face of Tour Ronde) I've been told late may / early june was the best time to climb. But I'd like to hear first-hand experience from people.
As for myself, I climbed some of the easier (AD) routes on Tacul triangle during long May weekends.