Has the gift of speaking in tongues ceased in the 21st Century church?

If you have not done so, you may wish to look at what I have said on tongues in 1 Corinthians 12-14:

• Spirituality and Spiritual Gifts - Part 1 (1 Cor. 12:1-3)
• Spirituality and Spiritual Gifts - Part 2 (1 Cor. 12:4-11)
• Spirituality and Spiritual Gifts - Part 3 (1 Cor. 12:12-31)
• What Is This Thing Called Love? (1 Cor. 13:1-13)
• Spiritual Gifts, Part 4: The Measure of a Gift (1 Cor. 14:1-25)
• Spiritual Gifts, Part 5: Spiritual Gifts and Self-Control (1 Cor. 14:26-40)

I should also say that I am not a strict cessationist -- one who believes that the gifts of tongues (among others) ceased with the apostolic age, and that they do not and cannot exist today.  The Scriptures teach that "tongues will cease" (1 Corinthians 13:8) but that is not the same thing as saying that tongues have ceased.  In context, it appears to me that Paul is saying that both tongues and knowledge will cease when our Lord returns (not just when the canon of Scripture is complete).

I do think that the gift of tongues did have a confirmatory function.  It certainly seems to have set the apostles apart in Acts chapter 2 (see also 2 Corinthians 12:11-12, where other miraculous signs set the apostles apart as God's spokesmen).  The gift of tongues served to confirm that Gentiles believers were equal heirs of the grace of God (see Acts 10:44-48, 11:15-18).

But 1 Corinthians 12 and 14 seem to indicate that the gift of tongues also benefits the individual believer, as well as the church, when they are interpreted (14:1-33).

I suspect that many claims to have experienced this gift may be questionable, but I dare not insist that all such experiences are false.
From the teaching of the New Testament (as I understand it) I expect that genuine tongues will be a human language, unknown to the speaker, and not mere babbling.  I also expect that this gift should be exercised as Paul has prescribed.  From 1 Corinthians 12 and 14 I would also have to grant that just because the gift of tongues is misused, this does not prove that the gift is false.  After all, every spiritual gift can be abused for personal gain.

As to your question concerning Acts 2:2-4 (I assume Acts 12:2-4 to be a
typo) and 8:37-39 (I am assuming this to be 8:17-19).  Note that the text never specifically says that these Samaritan saints experienced the gift of tongues.  We are only told that they were "receiving the Holy Spirit"
(8:17).  My assumption is that they were speaking in tongues, and that this was an evidence of their being baptized by the Spirit.

Note also that Simon did not ask to receive the Spirit (to speak in tongues?); he only asked to be granted the power to bestow the Spirit, as Peter and John had done (verse 19).  He wanted to have this power by paying for it, (and likely so that he could bestow the Spirit on others for personal profit).

Paul seems to have received the Spirit at the time of his baptism, as we can discern from Acts 9:17-18.  We do know that Paul claims to have spoken in tongues more than others (1 Corinthians 14:18-19), though he considered intelligible speech much more valuable.

As you have noted it does appear that the Spirit came upon men when the apostles laid hands on them.  But we must also note that Paul is very clear in saying that the gift of tongues is not given to every saint (1 Corinthians 12:30).  Thus, the gift of tongues did seem to confirm the baptism of the Spirit when bestowed by the apostles.  But after this the gift of tongues served the function of edifying the saints, if properly exercised.

In 1 Corinthians 12:11 Paul tells us that God's Spirit sovereignly bestows spiritual gifts on each believer as He wills.  I would take this to indicate at least two things:

(1) We should not tell God what gifts He can or cannot give.
(2) We should leave the bestowing of gifts to God, and not seek those gifts which He has indicated to be inferior (this inferiority I discern from 1 Corinthians 12:22-25, 31; and 14:1-19).

In 1 Corinthians 12:31 Paul exhorts the Corinthians to seek the greater gifts, and it is clear to me that tongues is not one of those greater gifts.
Thus, if we are to seek a spiritual gift, let us seek that gift which best serves to edify others.

One final word.  It is my firm conviction that there is no direct correlation between one's spiritual gift(s) and one's spirituality.  The possession of a certain gift does not make (or prove) one to be more spiritual than others.  Spiritual gifts are a matter of enablement for service; spirituality is a matter of character.