Currently, the weekly Tridentine Rite Mass is held Sunday mornings at St. Audeon's in High Street in Dublin. This church is also the "headquarters" of the ministry to the Polish community in Dublin. But as the Polish ministry continues to expand, the Tridentine Mass is going to move.
The new location will be St. Kevin's in Harrington Street. This is about a ten-minute walk south of St. Audeon's. Someone I know was at the 6 pm Saturday Vigil Mass yesterday evening, and the Parish Priest, Fr. James Larkin, announced it. Now the Holy Father's Summorum Pontificum comes into effect September 14th, but the switch will probably not happen for some time after that; apparently a news Parish Chaplain for the Tridentine Rite has to be appointed. The Tridentine Rite will be 10.30 am, and then the Novus Ordo Mass at 12 noon.
Currently Fr. Larkin is on his own in St Kevin's; this parish, like others in the city centre, has seen a population exodus to the suburbs over the last two decades or so; and this church is only a ten -minute walk from the Dublin Mosque, so there is a reasonably-sized Moslem population in the area.