A few thoughts/links further to Sophia's below.

Dubai 99% sure Mossad killed Mabhouh - "Dubai police chief said he was 99 percent certain that the Mossad was responsible for the assassination of top Hamas official Mahmoud al-Mabhouh , Gulf News reported on Thursday..."

UK, Ireland envoys: 'Nothing to add' - "Britain questioned Israel's role in the slaying of a Hamas terrorist Thursday after asking Jerusalem's ambassador to the UK to attend a crisis meeting at the Foreign Office. Britain has said it will investigate how some suspects in the assassination of Mahmoud al-Mabhouh came to have British passports -- and how they might have been forged..."

6 more assassins added to Dubai wanted list - "Dubai police broadened an international hunt on Wednesday for the hit squad that killed senior Hamas operative Mahmoud al-Mabhouh to 17 individuals, adding six more suspects to the original wanted list..."

Anyway, so we have a case of stolen identities. That means that anyone could have done this. Israel is likely, but could also be the victim of a setup. Once you start speculating down the espionage path any story you can dream up gains some plausibility.

Let's leave that aside for the moment and assume Israel's responsibility. Apparently some people believe this is a bad thing, in spite of the fact that Mahbhouh was an active operative for a declared enemy. This is a guy who certainly deserved death. Dubai should be embarrassed that this guy was in their country doing arms deals far more than Israel should be embarrassed for bumping him off.

Isn't this exactly the type of activity people like Goldstone and others are always calling for? Go in and get the bad guy directly. No collateral damage whatsoever. I suppose they might complain they should have gone in and arrested him, but they'd hardly complain less if the guy were kidnapped, and Mabhouh would hardly respond to an Israeli arrest warrant by showing up at an Israeli police station to turn himself in.

The people who complain about Israel's actions in this event (if, indeed, it was the Mossad that carried it out) are really saying that Israel shouldn't be able to defend itself in any way. They can't carry out military action. They can't carry out direct action. What can they do? Die, apparently.

But that's not going to happen.

More links: Tom Gross: Is Israel the only suspect over Dubai death?

And JStreetJive has an excellent post here: Mastermind of Coventry Bombing Demises in Instanbul.

Update: Hamas official accused of helping Mossad hit squad - "A key security operative of the Palestinian Islamist movement Hamas was under arrest in Syria tonight on suspicion of having helped an alleged Israeli hit squad identify Mahmoud al-Mabhouh before he was assassinated in Dubai, the Guardian has learned..."

Update 2: Noah Pollak has it right on several counts: A Dubai Victory

Update 3: Robin Shepherd: Scandal over Mossad use of UK passports curiously fails to materialise with Britons awe struck at Israeli daring