I think giving users free bumpers would not be a satisfactory fix.
The whole selling point for the IPhone as they portray it is it's sleek, slender size. If to use it, you have to stick on a rubber bumper, that surely takes away the appeal?
I guess for people who planned on putting a bumper on anyway, it would be OK, but it wouldn't help the bad press Apple is getting over this. They would be 'covering up' a problem by making the phone look less impressive.
The only way they can come out of this looking good is if they have done both of the following:
1 - Corrected the issue for all future production
2 - Have some way to issue a retro fit, either by a recall or by the option to have the issue 'fixed' in an Apple store.
If they don't do both of the above they will come out looking very poor in all of this. If they DO do it, it will probably reinforce the fan-boys views that Apple can do no wrong.
Either way, I think it's pretty poor that Apple have denied the issue and/or lied about it being a software issue for so long, so in my eyes their reputation is already dented.