It's called iPhone 4 Case Program [iTunes link] and you can find it for free in the App Store.
For those of you wanting to get a free white, pink, green, blue, or orange bumper will be disappointed. The only bumper available through this program is black.
But, there is a good amount of normal cases available:
- Incase Snap Case - Smoke
- Incase Snap Case - Clear
- Belkin Shield Micra - Clear
- Griffin Motif - Diamonds/Smoke
- Griffin Reveal Etch - Black/Black Graphite
- Speck Fitted Case - Black Tartan
- Speck PixelSkin HD - Black
I chose the Griffin Motif because I feel it would be a very different case compared to what I already have. Right now, I am using the Griffin Reveal and the iFrogz Luxe - Blue. It says it will ship in 3 to 5 weeks. I'm supposed to get an e-mail confirmation when it ships. I'll post updates here when I get that e-mail and when I receive the case.