Apple today launched the iPhone 4S across all three major carriers – Sprint, Verizon Wireless and AT&T. Preorders for the new device were shipping in two to three weeks, while wireless retailers opened early with considerably larger inventories than during past launches.

A customer service representative at an AT&T store this morning in Madison, Wis., said the store had around 60 iPhone 4 models when that device launched, but with the iPhone 4S the store was sitting on about 260 of the new phones, plenty to serve the approximately 60 customers who began lining up at around 7:30 this morning. The store opened early at 8 a.m. for today’s launch.

Customers looking to purchase the iPhone 4S will notice some differences to Apple’s AppleCare insurance coverage. AppleCare+, which costs $99 at purchase, now covers breakage. Customers can get a total of two replacements for $50 each, which covers such things as screen breakage or water damage.

While some consumers found the new iPhone underwhelming when it was unveiled, the new phone still managed to break iPhone preorder records, with 1 million customers placing orders in the first 24 hours.

D’Angelo Capriglione, one of the customers standing outside the AT&T store in Madison, said he decided to wait in line because he simply likes Apple products and always wants the latest and greatest. “The camera, too. That was big for me. It’s really amazing. The best camera out there,” he said.

Major upgrades to the iPhone 4S include an 8-megapixel camera, dual-core processor and the virtual assistant Siri, which features natural voice recognition, allowing users to simply speak commands to get information and complete tasks.

The iPhone 4S sells for $199 (16 GB), $299 (32GB) and $399 (64GB) with a two-year contract. The iPhone has dropped to $99 (16GB) and the 3GS is now free on contract.

Wireless Week managed to land a unit, so look for a complete review of the new device to be posted online next week.