I've also been wondering lately if Apple didn't already know prior to the launch of the phone.
I've always kept my iPhones in a case--a rubberized protective "Roots Canada" one--and planned to do the same with the new one.
But the Apple bumpers caught my eye. Unless I'm mistaken (and this does happen occasionally

) I don't remember bumpers being offered by Apple for any previous iPhones.
When I saw them I thought it was just Apple getting in on the device personalization business that they have usually not paid all that much attention to... but now that the Antenna issues have been exposed and more importantly, essentially resolved by use of those bumpers, I have to wonder about the reason for offering the $30 accesories together with the launch of the phone.
And offering them as an extra for $30 was sort of a "damned if you do, damned if you don't" thing. Giving them away free would have been tantamount to an admission of a known design flaw that they were correcting with a more attractive version of duct tape... charging for them? Well, we're all seeing the problem that's causing now with petitions, bad press and such...
Call me a conspiracy theorist, but I think the bumpers are an indication that Apple knew about the antenna issue before launch.