I'm sure the US keeps an eye on all potential oil producers these days, but I have to say I feel that the rationale for getting involved was something else.

To me, the magic words were "wanted members of Al-Qaeda." That was the basic political imperative. And as part of being seen to be chasing after these "wanted men" the US decided that the ICU was an obstacle and started looking for local allies in the Afghan conflict model. This led them to the Ethiopian government.

It's also worth mentioning that this was a good ground to try to recover some sense of "international unity" because there is a recognised government of Somalia who have been battling the ICU for a while.

Whether all this is a sensible action is of course an entirely different question.

However, I should end by conceding that the pattern of US interventions in the Bush-Cheney era has been that oil states and potential oil states get priority attention.