I just read about this over at the Shrine of the Holy Whapping. Cardinal Arinze, Prefect for the Congregation for Divine Worship, has released a statement that Catholics ought not to pronounce the divine tetragrammaton [YHWH] in biblical texts and within divine worship itself. This is because the sacred tetragrammaton was never pronounced in Christian contexts nor was it ever left untranslated in any of the languages into which the Bible was translated.
The Septuagint and the authors of the New Testament simply substituted Kyrios ("Lord").
Saint Jerome substituted Dominus and the English translators have denoted the sacred tetragrammaton by all caps: LORD. This tradition should be maintained.
View the official documents by clicking here.
Hat tip to the Shrine of the Holy Whapping.