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Took my iPhone into the Apple store today and they gave me a new one.
Genius said the rattling was not normal and was reason enough to give a replacement.

I traded in my black for a white 3G. No issues as of now.

Good luck!
 
I have a 16GB black 3g that has a rattle too. I did recently drop mine, but it was only a few feet onto carpet and it's in a case. I never really shook it previously so I don't know if it was there before the fall. Also it only seems to rattle when shaken in the vertical axis, not the horizontal axis and while it's hard to localize it seems to come from the bottom half of the iPhone. I asked a "Genius" about it today and he said he didn't think it was normal but since everything was working fine just to keep a close eye out for any dysfunction. Should I ask them to replace it?
 
Fix iPhone 3G rattle in under 6 seconds!

My Black iPhone 3G started rattling annoyingly after it suffered a little fall:eek:

The rattling is actually caused by part of the SIM ejector mechanism, as mentioned earlier in the thread.

It is easy to tell the difference between the slight rattling caused by the accelerometer, which sounds more suppressed and 'fixed', and the loose rattling which sounds like a tiny ball bearing is inside the iPhone caused by the SIM ejector mechanism.

To sort out the loose rattling sound, I just ejected the SIM tray, and replaced it. The rattling was gone:D It took two attempts, but that was it!

The mechanism is perhaps slightly temperamental, but its worth giving this a few goes before going to the bother of replacing iPhone, if yours is otherwise perfect!;)

Hope this helps!:)
 
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