The iPhone 4 has antenna issues.

Notice Steve is avoiding the antenna.
You would think that Apple would be sensitive to connectivity issues. Apparently not.
Since the iPhone 4 went on sale Thursday, June 24, numerous angry reports have begun to appear online about consumers having strange issues with the antenna. Namely, that if a user puts his or her hand over the new steel band that encases the iPhone, he or she will lose reception.
The first response from Steve Jobs was, “You’re holding it wrong.”
Apple has responded with a more corporate-ese worded statement:

Apparently Apple engineers have small hands (and everything else.)
“Gripping any mobile phone will result in some attenuation of its antenna performance, with certain places being worse than others depending on the placement of the antennas. This is a fact of life for every wireless phone. If you ever experience this on your iPhone 4, avoid gripping it in the lower left corner in a way that covers both sides of the black strip in the metal band, or simply use one of many available cases.”
Not-so-rugged baby buggy bumpers. Experts have found that yes, indeed, that when you put your hand on the bottom of the iPhone (something most people tend to do) to hold it while chatting, reception does take a nosedive. If you put on one of Apple’s new “Bumper” products, similar to a case, over the phone, reception does improve. The bumpers come in several colors, and sell for a suspiciously high $29.99 each. All the “Bumper” is is a plastic strip that goes around the iPhone. However, if it lets you hold the phone while speaking, some frustrated consumers may consider it a good investment. I believe that some entrepreneur will come up with a much nicer solution at a much lower price.
Trade-offs. In many smartphones today, the antenna is built into the bottom of the phone. That’s for two reasons: (1,) To meet FCC requirements regarding the specific absorption rate, or SAR (how much radiation is allowed to enter the human body), and (2,) the extending antenna went out of style several years ago. Smartphone makers are placing more constraints on themselves to make increasingly smaller phones with increasingly sophisticated features and design. They’re trying to fit larger batteries and more powerful processors into smaller packages, along with flashy materials, and a specific aesthetic. Those companies, like Apple with its iPhone 4, have to begin making certain choices and priorities. Jobs did not think the extended antenna would be that cool.

Cheaper than a "Bumper."
One early user had a simple answer: Just tape a popcycle stick to the iPhone for a handle. Problem solved.