Basically, Mahony and Curry are still fully vested, endorsed, and financially supported for life. The only change is, neither has to work another day of his life; that's what "relieved of public and administrative duties" boils down to.
Both can function within all of the authority of their power within the Catholic church.
The letter read at masses this weekend is, in essence, a "brace yourself, folks" notice to parishioners as to what is about to be revealed.
On a related matter, we are reminded this time of year, "Be sure to donate to the priest retirement fund."