I already thought of that but there it doesn't seem to likely to me. I did notice the recent admission from the US that some of the police and other Iraqi's recruited by the US where passing information to the other side.
But I see a lot more against that theory. For one, initial US reporting on the ambush was pretty bad, if they had been staged the information gathering would have been better. Second, it doesn't appear that any air support was available to either attacked group. I find it hard to believe that the US would stage a counter-ambush without a couple of attack helicopters near by. And finally, the US did just drive out of at least one of the attacks, if not both. The Iraqi's tried to block the unit's passage with improvised barriers and explosives, but the barriers where not sufficent to stop US tanks.
Jay