The crazy demon-possessed man living among the tombs is being forced by these demons to leave all his friends and family - all his support - and to live alone. The images of unclean things dominate this reading: tombs, demons, pigs, blood and finally death.
Jesus shows up and is ready to provide resurrection. He does so three times in this passage - once with the demoniac, once with the woman bleeding for 12 years and literally with the daughter of Jairus.
The opening scene of the tombs place us with the dead. It reminds me of when the women come to prepare the body of Jesus and the angel asks the question, "Why are you looking for the living among the dead?'
Jesus pulls the full potential of these lives forth and sets them free.
On another note, I've always associated the song, "Don't Drink the Water" by The Dave Matthews Band with the story of the demoniac. The tale told in the song seems to be from the perspective of a demoniac and when he is screeching and yelling at the end, it seems to be when he is being exorcised.
These stories are about separation from society and from God. Jesus comes to restore life and to restore these people in society. It is interesting how these two things go hand in hand.