Smudging is a Native American purification ceremony. They use the smoke from sage and some other plants, and an eagle feather is used to move the smoke over and around each person to drive away evil spirits. This was done at the beginning of a Sunday Mass, in place of the penitential rite as I mentioned. In researching this practice, I found that Archbishop Chaput of Denver, and even Pope Benedict during his visit to some place in the US southwest, have participated in this rite. I’m not clear whether this was during a Mass, however. In reading the GIRM, this would seem to be a liturgical abuse, but I don’t want to be “holier than the Pope”!