It surprises me a lot.

It pretty much ended the way the movie depicted, except historiclaly, Balin (or whatever Orlando Bloom's characters' name was) on the fifth day of the siege (or was the fourth day...) realised that there was no way he could win against Saladin and his army. So, in a move of desperation, B walked up to Saladin and told him that the Christians will surrender Jerusalem, and that all he asks for is the lives of the Christians (at this point Saladin has sworn that he would kill every last Christian int he city, as the Christians did to the Muslims and the Jews 80 or so years prior.)

Getting to the end of his ropes, B made the ultimatum that he will burn Jerusalem to the ground if Saladin insists on the deaths of every Christian in the city. Realise, the burning of the city would involve the mosque where Mohammad was believed to have ascended to heaven (well, the temple is built over a rock that is believed to be a piece of Paradise.) So, um, Saladin agreed that he won't slaughter the people. However, like all Medieval warfare (and especially the crusades), they spent 3 days hammering out terms of release.

Saladin would release one Christian for 10 dinars (I think that was a lots of money), and even after stripping the city of money thousands of Christians could not pay the ransom and as a result was sold to slavery. I know it sound bad, but it was the practice back then, and seriously Saladin was merciful enough to not kill them like the Christians did to every Muslim (women, men, children) when they first took over Jerusalem.

Um, I can't remember what happened to B after though (he is a historical character, he was the one who pretty much defended Jerusalem against Saladin’s army, but he didn’t have an affair with the Queen, and he was actually released by Saladin himself to Jerusalem because he told Saladin that all he wanted was to return to him wife and children and leave the Middle East. However, as soon as he entered Jerusalem, he was swarmed by the populace pleading for him to stay and defend the city against the invading army. He stayed and fought.

To clarify, B was a soldier of the Christians. He fought against Saladin in the last battle against Saladin (the one depicted in the movie, where the Christians got their arse handed to them), his army lost, and he was captured. This is when my memory get a bit murky, for the life me I can't remember if he managed to pay his own ransom or if in a show of mercy Saladin released him because of his sob story.