What is Baptism of the Holy Spirit? What is the Baptism of the Holy Spirit, and how does it differ from water baptism?  Do all Christians experience Baptism of the Holy Spirit?


EDIT

A few references to Baptisim of the Holy Spirit, or similar phrases, in scripture:


"He will baptize you with the Holy Spirit" -- Matthew 3:11, Mark 1:8, Luke 3:16
"one who will baptize with the Holy Spirit" -- John 1:33
"you will be baptized with the Holy Spirit" -- Acts 1:5, Acts 11:16
Baptism of the Holy Spirit refers to receiving the Holy Spirit into your life.

In John 14:16-17 (NIV), Jesus says:


  16 And I will ask the Father, and he will give you another advocate to
  help you and be with you forever— 17 the Spirit of truth. The world
  cannot accept him, because it neither sees him nor knows him. But you
  know him, for he lives with you and will be in you.


Later, after Jesus had ascended into heaven, the Holy Spirit came to the apostles at the feast of Pentecost.  The entire story is Acts 2, but specifically

Acts 2:2-3


  2 Suddenly a sound like the blowing of a violent wind came from heaven
  and filled the whole house where they were sitting. 3 They saw what
  seemed to be tongues of fire that separated and came to rest on each
  of them.


That is the Baptism of the Holy Spirit.

It's the Holy Spirit coming and filling us.  Once he enters our lives, we are forever changed. We have access to the Holy of Holies and have direct communion with God.