Late last night a visitor arrived at this blog via searching for "how to say the act of contrition in latin." It's a rather curious question; acts of contrition are not liturgical prayers, properly speaking, and are not even necessary in the celebration of the sacrament of Penance. A confessor must ascertain that a penitent is contrite before giving absolution, and asking for an act of contrition is a simple way of doing this. At the same time, the prayer allows the penitent to be reminded of his contrition and to exercise it on the occasion of absolution.
Nevertheless, it's an interesting question. I don't think there is any need or real purpose to praying one's acts of contrition in Latin. Doing so would probably come as a great shock to many priests, and not a few would surely find it very annoying. (Perhaps, however, in some cases, these might not be bad things.)
But if anyone feels called to pray an act of contrition in Latin, navigate over to one of the great Catholic treasures of the web, the Thesaurus Precum Latinarum, where you can find all of your preces latinae, and an Act of Contrition in particular.