In August 2007, I wrote (rather reproduced an Associated Press report) about bhut jolokia (the "ghost chilli") grown in northeastern India and claimed to be the hottest, rated at 1,000,000 Scoville units. The previous record holder, the Red Savina habanero, was tested at up to 580,000 Scovilles.
Bhut jolokia held the record for nearly three years until the end of last year when it was superceded by the Infinity chilli at nearly 1.18 million Scovilles then the Naga Viper at just over 1.38 million Scovilles, both grown in the United Kingdom.
The Sydney Morning Herald has reported that an even hotter chilli has been grown in Australia called the Trinidad Scorpion Butch T rated at 1.46 million Scovilles.
See also The Independent (UK).