What a timely post
I was just at the dealer and they told me I needed mine changed. I'm at 5,525 miles. Mind you, I've had the car for only 18 days now (04 bought used) so I was a bit surprised that I had to get it done already, thought I had another +/-500 miles to go. Well, the sales guy, Nate (he's awesome) sees me there waiting and asked why I was there. Told him about the hard/no start I had and that they told me I needed an oil change. Well, he was as surprised as I was since the oil was supposed to have been done before I took the car so, Nate had them do it for $0. Good thing too because I wasn't prepared to pay out $108 for it.
Anyways, Nate and I were talking and he said pretty much what has been said here, that the oil manufacturer recommends every 5,000 but that the service manager who has a RL (I didn't catch if it was Ion or Vue) does his every 3,000. I asked him if going to 5,000 would be adverse to the warranty and he didn't see a reason why it would be. But, I'm still going to remain faithful to the 3,000 because you never know....