SHAWN - In John 17 Jesus is praying for His apostles (at least that is what the chapter heading interprets it to mean when He says "those whom thou hast given me"). In verse 12, He says that none of them are lost but the son of perdition. It seems to be singular. In this case it seems to me that He is only referring to Judas Iscariot. Any insight that you can offer?
John 17:12 "While I was with them in the world, I kept them in thy name: those that thou gavest me I have kept, and none of them is lost, but the son of perdition; that the scripture might be fulfilled."

JOEL - From what I can tell from the scriptures and according to statements from some past Church leaders, "those whom thou hast given me" is refering to the twelve apostles and Jesus is most definately refering to Judas as a "son of perdition" in His prayer. When Jesus said: "that the scripture might be fulfilled", He is of course refering to the following prophesies made by the Psalmist:

"They took counsel together against me, they devised to take away my life." (Ps. 31:13)

"Mine own familiar friend, in whom I trusted, which did eat of my bread, hath lifted up his heel against me." (Ps. 41:9)

and that which Zechariah had said:

"If ye think good, give me my price; and if not, forbear. So they weighed for my price thirty pieces of silver. And the Lord said unto me, Cast it unto the potter: a goodly price that I was prised at of them. And I took the thirty pieces of silver, and cast them to the potter in the house of the Lord." (Zech. 11:12-13.)

All of which were fulfilled by the actions of Judas (Matt. 26:14-16, Matt. 27: 3-10, Matt. 26: 21, 25, Luke 22: 3). In His prayer Jesus did not mean that Judas is the only person on earth who could ever be a son of perdition; only that he is the only one of the 12 Apostles that is.

Another question one might ask is, if Jesus refered to him as a "son of perdition", does that mean that Judas is destined to join Satan and his angels in outer darkness forever, or was that only a temporary title that Jesus gave him? The short answer to this question is, we don't know.
President Joseph F. Smith provided his opinion on the situation of Judas:

"If Judas really had known God's power, and had partaken thereof, and did actually 'deny the truth' and 'defy' that power, 'having denied the Holy Spirit after he had received it,' and also 'denied the Only Begotten,' after God had 'revealed him' unto him, then there can be no doubt that he 'will die the second death.' (D. & C. 76:30-49.)
That Judas did partake of all this knowledge—that these great truths had been revealed to him—that he had received the Holy Spirit by the gift of God, and was therefore qualified to commit the unpardonable sin, is not at all clear to me. To my mind it strongly appears that not one of the disciples possessed sufficient light, knowledge nor wisdom, at the time of the crucifixion, for either exaltation or condemnation; for it was afterward that their minds were opened to understand the scriptures, and that they were endowed with power from on high; without which they were only children in knowledge, in comparison to what they afterwards became under the influence of the Spirit. . . .
No man can sin against light until he has it; nor against the Holy Ghost, until after he has received it by the gift of God through the appointed channel or way. To sin against the Holy Ghost, the Spirit of Truth, the Comforter, the Witness of the Father and the Son, wilfully denying him and defying him, after having received him, constitutes this sin. Did Judas possess this light, this witness, this Comforter, this baptism of fire and the Holy Ghost, this endowment from on high? It he did, he received it before the betrayal, and therefore before the other eleven apostles. And if this be so, you may say, 'he is a son of perdition without hope.' But if he was destitute of this glorious gift and outpouring of the Spirit, by which the witness came to the eleven, and their minds were opened to see and know the truth, and they were able to testify of him, then what constituted the unpardonable sin of this poor, erring creature, who rose no higher in the scale of intelligence, honor or ambition than to betray the Lord of glory for thirty pieces of silver?
But not knowing that Judas did commit the unpardonable sin; nor that he was a 'son of perdition without hope' who will die the second death, nor what knowledge he possessed by which he was able to commit so great a sin, I prefer, until I know better, to take the merciful view that he may be numbered among those for whom the blessed Master prayed, 'Father, forgive them; for they know not what they do.'" (Joseph F. Smith, Gospel Doctrine, 5th ed., pp. 433-435.)

We need to keep in mind the fact that the other eleven Apostles probably did not receive the gift of the Holy Ghost until the day of Pentecost(Acts 1: 4,5,8, Acts 2:1-4), after Jesus was crucified; which means that Judas certainly did not have it either at the time of the betrayal. The Doctrine and Covenants tells us:

"34. Concerning whom I have said there is no forgiveness in this world nor in the world to come—
35. Having denied the Holy Spirit after having received it, and having denied the Only Begotten Son of the Father, having crucified him unto themselves and put him to an open shame.
36. These are they who shall go away into the lake of fire and brimstone, with the devil and his angels— 37. And the only ones on whom the second death shall have any power;
38. Yea, verily, the only ones who shall not be redeemed in the due time of the Lord, after the sufferings of his wrath." (D&C 76:34-38)

Since Judas had not yet received the Holy Ghost as required in verse 35, he was probably incapable of committing the unpardonable sin.
The Doctrine and Covenants also tells us:

"And they that believe not unto eternal damnation; for they cannot be redeemed from their spiritual fall, because they repent not;" (D&C 29:44)

But Judas confessed his sin and was certainly very sorrowful for what he had done and did try to repent:

"Then Judas, which had betrayed him, when he saw that he was condemned, repented himself, and brought again the thirty pieces of silver to the chief priests and elders, Saying, I have sinned in that I have betrayed the innocent blood. And they said, What is that to us? see thou to that.
And he cast down the pieces of silver in the temple, and departed, and went and hanged himself." (Matt 27: 3-5)

These references suggest that, even though Jesus called him a "son of perdition" at the moment He was praying; in the eternal scheme of things, Judas might not be one of those destined for "eternal damnation" with Satan.
Many have debated this issue for centuries, and of course, only God knows the heart of Judas and only He can judge and determine his eternal future.