Approximately 500,000 units of the iPhone 3GS will likely be sold this weekend, says Piper Jaffray's Gene Munster. The analyst notes that while this represents relatively high demand, there are several mitigating factors which should make the 3GS launch pale compared to that of the 3G, which saw over a million phones pass by registers. Foremost is that the 3GS is a "less dramatic change in value
