There was a report out that said the iPhone4 was more fragile than its predecessors in terms of glass breaks...
Here's an interesting report that debuncts that theory...
In any case, yeah Apple support is top notch. My story was about 8-10 years ago, they replaced my 6 year old Powerbook G4 with a completely new one when I was calling in for a problem with a new Powerbook I had and happened to mention a recurring problem I had with my wife's Powerbook... They repaired my laptop under guarantee and said send in the old one to have their techs look at it... when it came back, it was the same gen laptop as mine - brand new (or refurb who cares).
Wife was very happy cos she's always getting my "hand-me-downs"!