How could Jesus be surprised? Matthew 8:5-10 (NLT)
  &nbsp;5 When Jesus returned to Capernaum, a Roman officer came and pleaded with him, 6 “Lord, my young servant lies in bed, paralyzed and in terrible pain.”
  &nbsp;7 Jesus said, “I will come and heal him.”
  &nbsp;8 But the officer said, “Lord, I am not worthy to have you come into my home. Just say the word from where you are, and my servant will be healed. 9 I know this because I am under the authority of my superior officers, and I have authority over my soldiers. I only need to say, ‘Go,’ and they go, or ‘Come,’ and they come. And if I say to my slaves, ‘Do this,’ they do it.”
  &nbsp;10 When Jesus heard this, he was amazed. Turning to those who were following him, he said, “I tell you the truth, I haven’t seen faith like this in all Israel!    


[Emphasis mine.]

If Jesus is God and therefore omniscient, how could He possibly be surprised by the Roman officer's words?
I don't have a definitive answer, but here are a few things to keep in mind about the text. When I consider some combination of these, it doesn't bother me that an omniscient God is "surprised".


The word in the text is not usually translated "surprised" as if it was an unexpected event. The sense is one of wonder or awe or marvel or (as in your translation) amazement. God being omniscient had to have known this ahead of time, but that doesn't preclude a sense of wonder.
Jesus was fully man. This means he felt and knew the things that men and know feel in addition to the things that God feels and knows. This could just the the human side of him expressing wonder.
The narrator of the story is NOT omniscient and, in spite of being guided by the Holy Spirit in the authoring of the text, is unable to know what was in Jesus mind and exactly how it worked. He described things as they appeared.
Jesus was deliberate communicator. If having a visible physical/emotional reaction to something would help his audience understand the situation better, I'm sure he could manage that. If we needed to know that that kind of faith was a wonderful thing, his marveling at it is a great way to mark it's importance.