No hints of this in the code. Or at least no one has found anything suggesting this so far in the developer pre release. No API, no settings, etc.
I don't think anything alluding to features not yet revealed is supposed to be present in the SDKs, but because of the sheer volume of materials that Apple has to release when they have hundreds of new APIs, they inevitably let a few hints slip out.
To help hedge against that, they make everyone receiving the beta SDK sign an NDA before being allowed to see it.
Anyways... this could be a cool feature, if done properly. I see various comments mentioning that previous phones have done it and then removed it in later models. Same thing happened with touch screens before the iPhone though, it was just that Apple was the first one to tune it to perfection, so maybe that'll happen with Haptic feedback, too. Or maybe without the guidance of Steve Jobs saying "No" hundreds of times, Apple is just throwing gimmicks in. We shall see.