I was perusing my local Honda dealer's parts room (while getting info on antifreeze), and took a look at the bottles of Genuine Honda oil on the shelf.
I believe it was the 5W-30 conventional that I specifically checked, but there was text on the back of the bottle saying something like, "Formulated for Honda by ExxonMobil."
I don't believe I looked at the 5W-20, but it wouldn't surprise me (especially since it's been corroborated in previous posts) to find that they say the same thing.