In reply to diddler:
Zillertal is a big place and most of the climbing & bouldering areas are way up at the end. The campsite in Mayrhofen is ok but a bit of a drive from the climbing (but you get to walk reverently past Peter Habeler's office). There's an ÖAV hut in Zillergrund but I've only eaten lunch there, no idea what it's like for accomodation.