Spirit Shell has now been changed to a 1 min cooldown (off the GCD). Once used, for the next 15 seconds, all of your greater heal, flash heal, heal, and prayer of healing casts leave an absorb instead of healing. The absorb lasts for 15 seconds. As far as I can tell, you cannot stack the absorb on one group - casting the same heal more than once simply extends the duration of the absorb, but not the amount.
I have to say, I like this much better than its previous incarnations.
Also, rapture now removes the cooldown on power word: shield. :D