The "orans" position is used in the logo of the Association of Contemplative Sisters.

The following is from a book by Balthasar Fischer. Prof. Fischer is now in his upper eighties, still does research and writing at the liturgy institute in Trier, Germany, and is known as the "Father of the Catechumenate" in the United States for his role in teaching the liturgies and rationale of the stages-and-steps in adult initiation. This is from his book "Signs, Words and Gestures" (Pueblo Publishing, 1981):

"Isn't it really surprising that during the 'presidential prayers' (the opening prayer or prayer of the day, the prayer over the gifts and the concluding prayer) and especially during the eucharistic prayer, the priest at the altar should adopt a posture diametrically opposed to the one we learned on our mother's lap? We brought our hands together for prayer and clasped them or pressed them against one another. At the altar, however, the priest separates them and holds them up to God like two empty cups: he [sic] extends his hands.

These two gestures of prayer were introduced into a liturgy of the Mass at different periods; both are meaningful and legitimate. To join the hands is to signify that the usual daily activity of these hands ceases for a moment and the hands come into their own, and will be, as it were, taking a holiday. Something like a holiday, after all, begins every time we pray.

But why does the priest do the opposite when he acts as president of the worshiping community and, in the name of all of us, pronounces the most important prayers of the Mass? Why does he extend his hands instead of bringing them together? This gesture is, in fact, older and more venerable than that of the joined hands; the latter came into use in the Mass as a gesture of prayer only in the Middle Ages, north of the Alps. But as early as the catacombs we find the Church or the soul represented as praying the way the priest and the faithful prayed at that time: with extended hands.

When hundreds of thousands of Eastern Christians went over to Islam, they took this gesture of prayer with them, and anyone who visits a mosque will see devout Muslims praying even today with extended hands...
On one occasion I gained new insight into this ancient gesture when I read somewhere that the Assyrians had a word for prayer which meant, "to open the fist." The fist, and especially a fist raised threateningly, is a sign of a highhanded, even violent person. People grasp things in closed hands when they are unwilling to let go of them; they use clenched fists to assault and hurt and, even worse, to beat others down so that they cannot get up.

Those who pray, however, are saying before God that they are renouncing all highhandedness, all pride in their own sufficiency, all violence. They open their fists. They hold up their empty hands to God: "I have nothing that I have not received from you, nothing that you have not placed in my empty hands. Therefore I do not keep a frantic hold on anything you have given me; therefore, too, I desire not to strike and hurt but only to give and to spread happiness and joy. For I myself am dependent on him [sic] who fills my empty hands with his gifts."

This old gesture of prayer, which the reform--thank God! has retained, is thus a whole sermon in itself. It is a sermon we must all take to heart, even if we ourselves no longer pray this way in public. For, at bottom, all of us extend empty hands to God when we pray. The thought I am trying to convey here is summed up in the final words that Martin Luther is reported as having spoken when he was dying: "We are beggars-- that's the fact."

"Signs, Words and Gestures" (Pueblo Publishing, 1981):