This is an example of signal loss that happens when holding the outer edge of the iPhone 4.
I repeated this test 20+ times with the same or similar results each time.
http://gizmodo.com/5571171/iphone-4-loses-reception-when-you-hold-it-by-the-antenna-band
If we could keep the idiocy down to a minimum in the comments, that would be great.
EDIT: I just wanted to say that I'm still very excited to have my new phone. This video was not posted so that I could rip on Apple. It is just here to be a reference for those who are curious.
That being said, I have also noticed the data drop out when trying to access webpages, not just on speedtest. Now that I know about this issue, I have noticed the effects during normal use (when I'm not trying to reproduce the problem). I only know this because I get excellent reception at my house (4 and 5 bars). Now I notice the phone will drop down to 1 or 2 bars if I happen to be holding it in the wrong position until I move my hand and then it jumps back up to 4 or 5 bars.