Sam Harris responded to this story with a blog post, which can be found here. In it, he talks about DMT and even quotes Terence McKenna at length. For a skeptic's perspective, I recommend it, it's a quick read.

Edit: Ah, I missed SWIMFriend's link. I thought it was odd when I saw this thread and didn't see a link to Sam's response.

Here's my links to the original article, a refutation of the "heaven" aspect by Sam Harris, and an interview with sceptiko the guy did.