Apple are not giving their Bumper for free even after the iPhone 4 Reception issues reported by users. But Cases.com is giving out free LifeGrip Cases for free which will prevent you touching the external antenna on iPhone 4.
They will give out a free purple, rose, black, blue or white LifeGrip silicone-base free case for free, you will need to pay $3.73 for shipping in US, and more if you are worldwide(For Singapore, it cost $28.50 for shipping!)
Check out Cases.com for your free LifeGrip case and hopefully you will feel better. 🙂