ANN - There is a scripture that says that "No man shall see God face to face and live" So my question is how is it that Joseph Smith could see God face to face?

JOEL - I assume the scripture you are refering to is D&C 84:21-22:

"And without the ordinances thereof, and the authority of the priesthood, the power of godliness is not manifest unto men in the flesh,
For without this no man can see the face of God, even the Father, and live."

In this scripture Joseph Smith is actually repeating something that Moses said while trying to get his people, who did have access to the priesthood and ordinances, to become sanctified so they could 'behold the face of God" ( See verse 23).
Also, the Lord made it a requirement, at the time he gave this revelation, that a man must hold the priesthood and have received its ordinances in order to see God. The Lord said: "this revelation...is in force from this very hour upon all the world..."(D&C 84:75). This would mean that prior to this revelation, neither the priesthood nor its ordinances(which were not on the earth at this time) were necessary for a man to see the face of God and live. When Joseph Smith went into the grove to pray, he had not been ordained to the priesthood by someone on the earth, neither had he received any of the ordinances.
In 1966 President Joseph Fielding Smith had this to say:

"If you will look at the date of this revelation, you will discover that it was given in September 1832, which was two years after the organization of the Church and several years after the appearance of the Father and the Son to the Prophet Joseph Smith. Therefore, permit me to emphasize this fact: There is no law or commandment which declares that the Father could not appear to a man in person when the Holy Priesthood was not among men on the earth. In this day when the divine authority is here and men are appointed to officiate in its ordinances, there is no occasion for the Father to come to any man who has no divine authority. At a time when the priesthood is conferred, and there are authorized servants who bear divine authority, there could hardly arise a time when the Father and the Son should have occasion to appear to any man who was without that authority." (Joseph Fielding Smith, Answers to Gospel Questions, Salt Lake City: Deseret Book Co., 1966) Vol. 5., pp. 84-85).

There are also other scriptural passages which indicate a person must have qualities other than the priesthood to see God. The Doctrine & Covenants states: "No man hath seen God at any time in the flesh, except quickened by the Spirit of God" (D&C 67:11). After all is said and done, we find several aspects to the subject of seeing God. No doubt today men must hold the priesthood to see God, but prior to the restoration of the Priesthood, this was not necessarily so. At the time of the First Vision, what was required to see God was humility, faith, and the spirit of God.

Another thing to consider is that no mortal man can withstand the presence of God unless his body is transfigured; a temporary physical and spiritual change that comes over a person so that they can behold the glory of God and stand in His presence. Transfiguration bestows on individuals a temporary condition compatible to that of deity and allows them to see God face-to-face. This is what happened with Moses when He spoke with God "face to face" (Gen. 32: 30, Ex. 33: 11) Soon after Moses' call, for example, he was transfigured so that he could withstand God's power; he later wrote:

"But now mine own eyes have beheld God; but not my natural, but my spiritual eyes, for my natural eyes could not have beheld; for I should have withered and died in his presence; but his glory was upon me; and I beheld his face, for I was transfigured before him." (Moses 1:11).

Jesus was transfigured before Peter, James, and John on the Mount of Transfiguration so that "his face did shine as the sun, and his raiment was white as the light" (Matt. 17:2). On the same occasion, the apostles were similarly changed, enabling them to remain in his transfigured presence. After Jesus touched His Nephite disciples they were "caught up into heaven" and later reported:

"whether they were in the body or out of the body, they could not tell; for it did seem unto them like a transfiguration of them, that they were changed from this body of flesh into an immortal state, that they could behold the things of God." (3 Nephi 28:15)

Another important ingredient is the strength of one's faith. After seeing the finger of the Lord, God said to the brother of Jared:

"Because of thy faith thou hast seen that I shall take upon me flesh and blood; and never has man come before me with such exceeding faith as thou hast; for were it not so ye could not have seen my finger." (Ether 3:9)

So along with Joseph Smith's great faith his body was probably changed(transfigured) so he could see God with his spiritual or transfigured eyes.