Yes, looks like it started in February. Not mediation, but 'on papers' adjudication. Details here:
http://www.cedr.com/aviation/
Currently, just Thomson and BA have signed up and there is no case history available.
Looks cheap - £25 fee, and only if none of the passenger's complaint is upheld - and simple, so *might* be a worthwhile alternative to MCOL, recourse to which is still not precluded if one remains unhappy with CEDR's decision.