This one shook me, because I fly there often and, indeed, I was flying in the same place a few days before the accident. Anyway, the final accident report has been published by SESA
http://www.bfu.admin.ch/common/pdf/2141.pdf (in French).
Rough and ready translation of the probable cause = loss of control following loss of visual references and spatial disorientation associated with an unsuccesful attempt to avoid cloud. Hit ground with practically zero ground speed, >4000 ft/min RoD, 25 deg nose down, 10 deg roll left, cruise power (possibly a spin but the report doesn't say so explicitly). Pilot was PPL/ME/IR.
Report also cites "inappropriate tactical aproach to flying" in mountainous region/weather conditions as a contributory factor.
Very sad.