Forensic evidence afterwards could implicate the Iranians but I think we now live in a world where people wouldn't care/wouldn't believe it. We've seen the old "spark in the central fuel tank" thing before and people don't necessarily believe it. If the Iranian ship goes down, the world will blame the Jews for the unprovoked attack.
With all the instability in the Arab world, I think some folks would see this as an opportunity to unite against a traditional enemy.
The Flight 800 thing continues to amaze me. Any bomb or missile that caused the explosion would have had to violate the laws of physics, but people will still tell you that the really crazy theory is that a palne with 93,000 flight hours would have a mechanical failure.