A few reports are surfacing that claim the current reception problem with the iPhone 4 could be an issue with the phone's OS software instead of the phone's construction.
Similar to the recent videos showing the grip on the iPhone 4 resulting in signal loss, others have released videos showing the same things happening on older models after having upgraded to iOS 4. This indicates the problem is in the operating system instead of the phone's hardware, which is promising for people who have been impacted by the reception issue.
In looking at what is happening, the root of this problem is in the hardware. When you physically bridge two parts of the phone with your hand the signal drops, and then reappears when you change your grip. This happens because of interference in the RF signal, where the user's hand will either shield, ground, or introduce noise in the signal. This will happen to some degree on every electronic device that uses RF signals (bluetooth mice, wifi routers, and other phones), but may happen more prevalently on the iPhone 4 because of its exposed antennas.
Check out CNET's demonstration of this problem on the new iPhone!
While the root of the problem is in hardware, there is a second component, which is how the software handles fluctuations in signal quality. This noise introduction alters the signal's characteristics in such a way that the phone can no longer identify it. Since this happens on both newer and older iPhone models that are running iOS 4, it indicates the current OS version is not handling signal fluctuations very well.
Therefore, fixes coming in the form of an OS or firmware update will not necessarily eliminate the situation for the iPhone 4, but may help it by increasing the device's tolerance of noise in the RF signal. Even with a software fix the iPhone 4 may still be susceptible to greater signal fluctuations, but we can hopefully look forward to an update making this problem less noticeable. Meanwhile, the only fixes are to change your hand grip (or using no grip with headphones or a bluetooth earpiece), or using a protective case.