This analysis from David Bernstein is worth quoting in full:
Bush and Sharon: For all the handwringing of the American (not to mention world) media, the dynamic is very simple: Bush has made it abundantly clear that he wants the Palestinians to have a responsible government that fights terrorism, and wants the Israelis to move toward a settlement that turns over sovereignty of Gaza and most of the West Bank to a Palestinian state. No progress was being made in either direction for some time. Then, Sharon announced a unilateral withdrawal from Gaza. Self-interested, sure, but also a political risk that breaks the impasse that had developed, and a potential momentum builder. Bush looked in vain for a reciprocal gesture from the Palestinians. He got nothing. Worse then nothing, the Palestinians have been busily discussing how to bring Hamas into their government. Result: political rewards for Sharon, a cold shoulder for the Palestinians. It was almost two years ago that Bush made it clear that he would judge the Palestinian leadership by one criteria: its willingness to fight terrorism. Why, two years and no willingness to fight terrorism later, it expects "evenhandedness" from Bush shows that they simply don't understand the man.
Neither I nor my fiancee will ever forget the celebrations the Palestinians had when they heard the news on 9-11-01.