Piecing together information from various reports, this is a composite picture of what happened:
The attackers were American, Israeli, or of unidentified origin, using perhaps gunships, F15s, F16s, or Hermes 450 drones and Eitan UAVs, taking off from Eritrea, Djibouti or possibly south of Tel Aviv.
In January and/or February 2009, they attacked 1-2 convoys, consisting of 4-23 trucks, 1-3 times. The attacks left 39-800 dead (including some Iranian escorts or Revolutionary Guards), and there were between 0-50 survivors, which possibly included an Ethiopian mechanic. The attack left 18 craters, ranging in size from 160-430 metres (!).
In addition, 0-1 ship[s] were sunk. The convoy[s] were smuggling either goods, people, G4s and Kalashnikovs, or 120 tonnes of arms and explosives, including anti-tank rockets and Fajir rockets with a 25-mile (40-kilometre) range and a 99-pound (45-kilogram) warhead.
Not exactly illuminating. He concludes:
It is quite possible that any one of these reports may be accurate, or perhaps none of them - or any combination of truth or falsehood in between. However, what is notable is that although we simply do not know the details of what happened, that has not stopped the story reaching the mainstream media with certainty that Israel's long arm stopped a conspiracy involving Iran, Hamas, and smuggled weapons bound for Gaza.
Obscure or fringe sources were deemed passable in piecing together this story that in other situations would be rejected for being too unreliable. This was nearly the case here, relegated at first to blogs, but the significance of the ideal version of the story was too good to miss out on, and so graduated to mainstream Sunday newspapers and weekly news magazines.
Previous discussion of this on Arabist.net: