In Dante's story, those who were in Limbo but taken to Heaven were
the shade of our First Parent [Adam], Abel his son, and that of Noah; of Moses the Legislator, and obedient Abraham the Patriarch; David the King; Israel with his father, and his sons, and Rachel, for whom he did so much; and many others
(Canto IV, lines 55–61)
These appear to be those of the Jewish people and their forebears who knew God (as for example Adam and Abel) and who worshiped Him obediently ("obedient Abraham").
Homer, Horace, Ovid, Lucan, and Virgil, on the other hand, were pagans; "they worshiped not God aright" (Canto IV, line 38), and Dante cites this as the reason they were not taken up to Heaven.
The Catholic Church, nowadays, doesn't say much about Limbo; the term does not appear in the 1992 Catechism. In 2007, the International Theological Commission (a body of Catholic theologians overseen by the Congregation for the Doctrine of the Faith) issued a document titled "The Hope of Salvation for Infants Who Die Without Being Baptized". This document is the most wide-ranging discussion of the question of Limbo that has been issued since the Second Vatican Council. Certain news stories published just before the document was released reported that it "closed the doors" of Limbo and concluded that Limbo did not exist; that conclusion was premature, but certainly the Church has recently focused much more on the hope that those who died without baptism, especially without the possibility of baptism, may somehow attain salvation:
Our conclusion is that the many factors that we have considered above give serious theological and liturgical grounds for hope that unbaptised infants who die will be saved and enjoy the Beatific Vision.
("The Hope of Salvation", paragraph 102)
So how does this apply to the patriarchs, the noble pagans, and the Harrowing of Hell? The Catechism states:
Scripture calls the abode of the dead, to which the dead Christ went down, "hell" - Sheol in Hebrew or Hades in Greek—because those who are there are deprived of the vision of God. Such is the case for all the dead, whether evil or righteous, while they await the Redeemer: which does not mean that their lot is identical, as Jesus shows through the parable of the poor man Lazarus who was received into "Abraham's bosom": "It is precisely these holy souls, who awaited their Savior in Abraham's bosom, whom Christ the Lord delivered when he descended into hell."
(paragraph 633; the last quotation is taken from the Roman Catechism)
Who, then, are the "just"? Might they include these "noble pagans" Dante refers to? Again, the Catechism has something to say:
The Bible venerates several great figures among the Gentiles: Abel the just, the king-priest Melchisedek - a figure of Christ - and the upright "Noah, Daniel, and Job". Scripture thus expresses the heights of sanctity that can be reached by those who live according to the covenant of Noah, waiting for Christ to "gather into one the children of God who are scattered abroad".
These of course do not, and could not, include the great poets Dante refers to. Nevertheless, as the Church begins to reflect on the great mercy and salvific will of God, it may hold out hope that they, too, are somehow saved.