This afternoon Harrah's Rincon posted this on it's Facebook page in response to my question about details for the changes:

Very soon you’ll be receiving communication via mail or email about improvements we’re making to Total Rewards in 2013. We’re introducing Tier Credit Bonuses for our updated Tier Levels and new exciting Tier Benefits! Earning starts on January 1, 2013, with new benefits available by April 1, 2013.

Well, this is an interesting spin, isn't it?