Launching rockets at civilians is inexcusable, but there's also something very disturbing about Tzipi Livni's unfortunately-these-things-happen approach to the civilian deaths in Gaza. Hamas has been responsible for some pretty nasty things, and there's no question they should be undermined. But it seems to me that the best way to bolster their organization is to provide an external threat--even Fatah, their rival faction with which they had a brief civil war, is taking Hamas' side in this situation. I worry that Israel is doing the same thing we did in Iraq--the minute we invaded, we provided a rallying cry and apparently knocked a lot of fence-sitters into the radical camp. I think for every militant the Israelis kill, they'll add 20 more recruits to the cause they're trying to crush.
The irony is that according to this Washington Post article, Israel may have squandered an opportunity to weaken Hamas without using force, giving growing resentment toward the group since the 2006 parliamentary elections.
The last thing I want to say is just a cheesy observation on how lucky we actually are. It's been 144 years since we've had to worry about civil war and 60 years since we've had to really worry about direct military invasion. We take it for granted that we fight with ballots instead of bullets, and that none of our neighbors will bomb us tomorrow. We shouldn't--because for much of the world and for most of human history, that has not been the case.