iPhone 4S pre-orders tally 1 million in 24 hours

If you had any doubt that the new "underwhelming" iPhone wouldn't sell, consider it shattered.

Apple this morning announced that pre-orders of its newly-announced iPhone 4S have topped one million in a single day. The previous single-day record for the device was 600,000, held by its predecessor, the iPhone 4.

Why the bump? A few potential reasons:

1. Apple added more customers to its portfolio since the previous model was announced;
2. The nearly three-month "delay" off its traditional announcement schedule meant more customers were eligible for upgrades;
3. The Siri intelligent assistant is an attractive feature;
4. The death of co-founder Steve Jobs pushed the company to the forefront of the world's collective consciousness.
5. The addition of Sprint to the carrier mix.
6. We're finally into holiday territory.

My money is on a combination of Nos. 2 and 4.

See also: iPhone 4S: Bluetooth 4.0, the quiet innovation | How Apple's iPhone 4S preorders stack up historically | Unlocked iPhone 4S available in November | Why I ordered an iPhone 4S | Can Apple win its iPhone 4S bet that 4G isn't ready for masses?

The new iPhone 4S looks identical to its predecessor but carries an upgraded dual-core A5 chip, a new camera and of course Siri.

The real telltale sign will be when Apple opens all 245 of its U.S. brick-and-mortar doors to sell the $199-and-up device next Friday, Oct. 14. Will word-of-mouth play a part in increased sales, or will its resemblance to the previous model stunt buzz? Regardless, Apple is doing its part to keep a steady stream of devices flowing from its warehouse shelves by selling the device in 22 more countries by the end of October.