Today Pope Benedict XVI has issued what is called a Motu Proprio, that is an Apostolic Letter, called Summorum Pontificum which concerns the use of the Roman liturgy prior to the reform of 1970. In other words, it deals with the Latin (sometimes referred to as the Tridentine) Mass which was used throughout the world prior to 1970 when the changes suggested by Vatican Council II were implemented.
In the Explanatory Note issued by the Holy See Press Office, it is explained that the Roman liturgy will have two forms: the ordinary form promulgated by Pope Paul VI in 1970 (sometimes called the Novus Ordo) in which there is an official edition in Latin and translations in many languages; and the extraordinary form which was promulgated by Pope John XXIII in 1962. There is no intention to create two different rites -- there is but one rite with two forms. It is hoped that this will be a unifying effort and will help bring about an interior reconciliation in the heart of the Church.