On Friday, Apple said it had been working for three weeks to try and come up with a fix for the antenna problem. Whether the 'free cases for all' bit that came next was the final solution or just an interim fix is not known. However, Steve did say they'll reevaluate in the fall and jokingly added, "Maybe Eminem will come out with a band-aid that goes over the corner and everyone will want that."
Well, it looks like one opportunistic Etsy user took Steve's joke and ran with it. For just under five bucks you can get five "antenn-aids." They look just like the plasters you'd put over a scraped knee or elbow, but they're stickers for the corner of your iPhone 4. The idea is that by bridging the gap between the two antennae with something other than your finger or hand, your death-grip will have a less than deadly affect.
It's $4.99 (plus at least $0.99 shipping) more expensive than the free case Apple will give you, but if you're not a case person, it's a fairly cheap alternative. You could also just buy a pack of normal plasters and trim them down to size.