In every major religion there is tongues speaking. Therefore, just because someone speaks in tongues it does not necessarily mean it is from the Holy Spirit. It can be demonic, and it can also be human.
We need to be careful with this because if we start using sign gifts as a means for determining whether or not someone or something is of God, and ignore the scriptures, then we will find ourselves in a dangerous place spiritually. This is why we have as many false teachers in the church today.
Mat 24:24 For there shall arise false Christs, and false prophets, [b]and shall show great signs and wonders[/b]; insomuch that, if it were possible, they shall deceive the very elect.
Mar 13:22 For false Christs and false prophets shall rise, [b]and shall show signs and wonders[/b], to seduce, if it were possible, even the elect.
2Th 2:8-10 And then shall that Wicked be revealed, whom the Lord shall consume with the spirit of his mouth, and shall destroy with the brightness of his coming: Even him, whose coming is after the working of Satan [b]with all power and signs and lying wonders[/b], And with all deceivableness of unrighteousness in them that perish; because they received not the love of the truth, that they might be saved.
Mat 7:22,23 Many will say to me in that day, Lord, Lord, [b]have we not prophesied[/b] in thy name and in thy name [b]have cast out devils[/b]? and in thy name done many [b]wonderful works[/b]? And then will I profess unto them, [b][i]I never knew you: depart from me, ye that work iniquity[/i][/b].