I found this for the early saver program.
"Price protection applies to new Early Saver bookings only and requires payment of a non-refundable and non-transferable deposit. Applies to cruise fare only. Applies only to a Carnival.com or Carnival advertised fare available to the general public and excludes group rates, membership programs, charters or other Travel Agent promotions not offered by Carnival to the general public, including but not limited to travel agent rebates. "
Read it all here:
Early Saver Program | Carnival Cruise Lines
Exotic Western Caribbean - Dream (B2B) - November, 2013 (Our Honeymoon)
Eastern Caribbean - Dream (B2B) - November, 2013 (Our Wedding)
Mexician Riviera - Spirit - November, 2011
Western Caribbean - Freedom - January, 2011
Southern Caribbean - Miracle - November, 2010
Western Caribbean - Liberty - November, 2008
Eastern Caribbean - Valor - October, 2006