For anyone who is interested, I've just checked MyCunard and the pass information has been updated to show spa passes. (Only copied the QM2 here.)
Queen Mary 2's Spa Passport
This pass includes the use of the Aqua Therapy Centre, which comprises a whirlpool, aqua therapy pool with chaise lounge, neck and back jet massage, cascading waterfall shower, reflexology basins, sensory showers, Finnish sauna, aromatic steam room, herbal sauna, and ice fountain. A bathing suit is required.
1 day – $40
3 days – $75
6 days (transatlantic crossings) – $105
A Spa Passport is complimentary on the day of any Health & Wellness, Massage, Body or Skin Care treatment.