A brief update:
Three (anti-Israel) British newspapers claim that the explosion happened while Israel was shelling, not after.
A German newspaper claims it has proof that the shelling was staged. It raises good questions but proving a conspiracy would need much more than questions. At the very least, the cameraman at the scene "first" has no credibility whatsoever.
History News Network has a scoop of an email from the surgeon that removed the shell fragments who positively identifies them as being from Hamas bombs.
Great blog entries from Israel Matzav and Daled Amos.