Around 600,000 people pre-ordered the iPhone 4, the previous record, though it's worth pointing out, which Apple doesn't, that the iPhone 4S is available on more networks.
The iPhone 4 was limited to one network in the US, while the iPhone 4S is available on three networks. You might therefore cheekily ask if that figure shouldn't be higher...
"The first day pre-orders for iPhone 4S have been the most for any new product that Apple has ever launched," said Philip Schiller, Apple’s senior vice president of Worldwide Product Marketing.
The new iPhone 4S, which was announced last Tuesday, will go on sale in the UK at 8am on Friday 14th October.