I apologize for the typo. The hotfix should (and now does) read:
"The priest tier-13 two-piece set bonus should again trigger a 23-second Temporal Boon for non-
Discipline priests, up from 20 seconds."http://us.battle.net/wow/en/blog/4023884/Patch_43_Hotfixes-12_6_2011#blog
Power Infusion continues to get a duration of 10 seconds on Temporal Boon, as intended.