This short video shows the iPhone 3GS running Erica Sadun's 'Strength' app and showing a reduction in signal strength when held in the hand. While the signal issues aren't as pronounced as they are on the iPhone 4 and usually don't result in dropped calls, this does show that most cell phones show signal attenuation when held in the hand.

[youtube]http://www.youtube.com/watch?v=be2oLapa5xM[/youtube]
[Via]
<a href="http://dailyiphoneblog.com/2010/07/09/video-iphone-3gs-signal-strength/">

[Read the original blog post]
</a>