Can I get Apple to swap my iPhone 3G for a new 4G for free?

I've heard that Apple will replace with the latest model phone. But how do I get them to replace my phone? There's nothing really wrong with it but I'd like the 4G. I guess I could pay for the upgrade but I really don't want to extend my contract...and plus, I feel like the frustration and crappy service from AT&T has earned me a freebie! Do I need to call Apple and report it as lost or stolen? I've had the 3G for almost 2 years now and I didn't buy the extended warranty coverage, can I even get a free replacement?