DPinTX mention on this thread that an Apple Tech told him some of the phones' 3G antenna's were too short. They swapped his phone out for a new one and that solved his problem. I was wondering where I'd heard this before: Ding! David Pogue's criticism of the GPS function. He said someone at Apple told him the directions wouldn't work well because the antenna was too short. Many people thought that didn't make sense - unless they were actually talking about the 3G antenna - which is how the google maps would load. I wonder if Pogue thought he meant the GPS antenna when in fact he meant the 3G antenna??
Since antenna length has to be a specific fraction of wavelength, this is a real possibility for the dropped call issue.
As for GPS, the issue with antenna length might impact the number of satellites you can lock on to at once because the GPS signal is fairly weak and prone to interference.
There's a reason that a good dedicated portable GPS costs more than an iPhone and is often larger (and they all have much larger antennas) and heavier. When you combine devices, you make trade off considerations, and the iPhone probably made too many.