Well, this article says they are "possibly" the hottest, not that they are. And according to their tests, the Dorset Naga came in at 960,000 SHU. They say the tests that gave results of 1.6 million weren't correct. I also note the wording where they compare it to the Red Savina. While they mention that the Red Savina is no longer the world record holder, they...oops! don't mention the pepper that beat it, or the reported Scoville level. Which is good business, since they want you to buy their Dorset Naga and not a Bhut Jolokia.
Now, I would expect a pepper that was grown in New Mexico to come in with more scovvies than the same plant grown in the UK. It's hotter and dryer in New Mexico. Well, at least the part where the Chile Pepper Institute is. So, that 960,000 SHU might easily climb over a million if it were grown in New Mexico.
So, that was why I keep saying, although fans of the Naga and detractors of Guinness ignore it, that the Naga may well be hotter than the Bhut Jolokia, but we won't know until they are grown together under controlled growing conditions.
But right now, today, the Bhut Jolokia holds the record for the world's hottest pepper.