This, from the USCCB's website:
The Missale Romanum (the Roman Missal), the ritual text for the celebration of the Mass, was first promulgated by Pope Paul VI in 1970 as the definitive text of the reformed liturgy of the Second Vatican Council. A second edition followed in 1975.
Pope John Paul II issued a revised version of the Missale Romanum during the Jubilee Year 2000. The English translation of the revised Roman Missal is nearing completion, and the Bishops of the United States will vote on the final sections of the text this November. Among other things, the revised edition of the Missale Romanum contains prayers for the observances of recently canonized saints, additional prefaces for the Eucharistic Prayers, additional Votive Masses and Masses and Prayers for Various Needs and Intentions, and some updated and revised rubrics (instructions) for the celebration of the Mass. The English translation of the Roman Missal will also include updated translations of existing prayers, including some of the well–known responses and acclamations of the people.
This website has been prepared to help you prepare for the transition. As this site continues to be expanded, you will find helpful resources for the faithful, for the clergy, and for parish and diocesan leaders.
May this process of the implementation of the revised Roman Missal be a time of deepening, nurturing, and celebrating our faith through our worship and the celebration of the Sacred Liturgy.
You can access the UCSSB's Roman Missal website here.