In fact, according to an anonymous source speaking to Bloomberg, Apple's senior antenna expert, Ruben Caballero, voiced concern to Jobs during the early design phase of the iPhone 4 last year that the external antenna design could lead to dropped calls.
Additionally, another anonymous source told Bloomberg that a carrier partner reportedly voiced concerns to Apple as well. It's unclear which carrier; while AT&T is Apple's most prominent carrier partner, it's obviously not the only one.
The iPhone 4's antenna issues have been labeled the "death grip." If the gap between antennas on the lower left-hand side of the device is bridged with skin, many have seen signal strength, or even calls, drop.
Because the iPhone 4 has multiple antennas, the metal bezel could not be constructed in one piece. It would have to be separated into sections, and therein was the issue that Caballero raised, and which is being seen. Caballero said that if a user covered one of the seams between the sections, their finger would act as a conductive material, interfering with the signal.
While it is true that other smartphones exhibit the same behavior when gripped, their signals do not attenuate to the point of a call drop, because the iPhone 4 is unique in its antenna design. While a nice industrial design, it may be a poor technical design.
Apple has scheduled a press conference for Friday morning to discuss the iPhone 4. While not specific in its invitation, the conference will undoubtedly cover the issues with the iPhone 4 antenna design.