Binding and loosing

I read something in my Bible time yesterday that left me puzzling:

" Then said Jesus to them again, Peace be unto you: as my Father hath sent me, even so send I you. 22 And when he had said this, he breathed on them, and saith unto them, Receive ye the Holy Ghost: 23 Whose soever sins ye remit, they are remitted unto them; and whose soever sins ye retain, they are retained." John 20:22, 23

What could this mean? That the apostles or even any Christian can forgive or withhold forgiveness from people? That they could act in God's place? There was a reference to Matthew 18:18:

"Verily I say unto you, Whatsoever ye shall bind on earth shall be bound in heaven: and whatsoever ye shall loose on earth shall be loosed in heaven." (This verse follows verses specifically talking about the steps of church discipline.)

I began to read various commentaries, and found what I thought to be the best explaination: these verses have to do with church discipline. For example, the church leaders (starting with the apostles whom Jesus breathed on) are given the responsiblity of dealing with backslidden Christians. If there's a woman in the church who is living with a man she's not married to, and won't respond to the steps laid out in Matt 18:15,16 (one person speaks to her about it, then 2-3 more if she doesn't respond), the next step is to bring the matter to the elders of the church. They will then decide if she should be put out of the church. Their decision is binding her, making a boundary concerning her. If she repents, they'll loose her from it, and let her join back into fellowship. This is serious business, even to the point of being recognized in heaven.

Here's the site I learned the most from: http://www.geocities.com/dcheddie/john20_1.html

I thought this a very interesting study, especially as all I ever heard about binding and loosing had to do with binding demons and loosing Christians from their grasps.