Since I cannot fathom why Sharon wants to push forward with his plan to expel all Jews from Gaza, and since I try to give everyone the benefit of the doubt (and also since I never really liked conspiracy theories like "Sharon is using the explusion to divert attention from his own scandals"), here is a theory I just made up:
Sharon completes the "disengagement." He has a secret agreement with President Bush that Gaza will be a test environment, a model statelet for Palestinians. The Palestinians will have some fixed period of time to turn Gaza into a miniature democratic Palestine - no Hamas gangs, truly free elections, the building of a real infrastructure, no attacks against Israel from Gaza, the building of industries and exports to other countries. In other words, here is the last chance to see if Palestinians can act like adults.
If the Palestinians pass the test, then Israel continues withdrawing from other territories. If not, game over - Israel redraws the West Bank (and perhaps Gaza) on her own terms and says "See? Why should we want to create a state for people who are clearly not mature enough, after decades of whining, to run one responsibly?"
Now, even if this is the plan, it is folly. But maybe this is what is going on. I could at least understand something like this, even if I don't agree.