Apple's redesigned 27-inch iMac may not be widely available until January 2013, but a number of early pre-order customers are now seeing delivery dates listed between Dec. 24 and Dec. 31, 2012.

MacRumors, citing recent forum posts by iMac customers, reported on Sunday that some early customers have already seen their credit cards officially charged by Apple, with email notifications now listing their 27-inch desktop computer is "Preparing For Shipment." This stage, where the computers are ready to be sent off to the delivery companies, means customers can't cancel or change their orders.

Only US customers have reported the status change in their orders; yet, what's interesting to note is that unlike previous iMac releases, where the simplest stock iMac models were shipped first, many Apple customers expecting to receive their new 27-inch iMacs this month actually ordered custom built-to-order configurations.

Apple first opened up pre-orders for the 27-inch iMac on Nov. 30, the same day the company released its 21.5-inch iMac to the public. Orders placed on that day listed 3-4 week waiting periods, but that changed on Dec. 7, when the 27-inch models started listing a "January" shipping date online.

The 27-inch iMac is roughly 20 inches tall, 26 inches wide, and weighs about 21 pounds -- almost double the weight of the 21.5-inch iMac. The desktop features a 2560 x 1440 display resolution on its 27-inch (diagonally) IPS screen.

"Everything you see on the big, glossy display -- from skin tones and dark shadows to bright blue skies and green fields — is rich and vibrant," Apple says on its website. "And the colors are more true to life, too. That’s because every iMac display is individually color-calibrated using state-of-the-art spectroradiometers to match color standards recognized around the world."

The most basic 27-inch iMac is powered by a 2.9 GHz quad-core i5 processor from Intel, with Turbo Boost up to 3.6 GHz. The higher-end model features a 3.2 GHz quad-core i5 chip with 3.6 GHz Turbo Boost, but Apple will also configure custom models with the speedy 3.4 GHz i7 chip from Intel, which has a Turbo Boost up to 3.9 GHz. 

From a graphics perspective, the 27-inch iMac is powered by GeForce GTX from NVIDIA -- the lower-end model has a 660M chip, while the higher end desktop is powered by a 675MX graphics processor, but those customers can further choose to upgrade to a 680MX processor for enhanced performance.

The iMac comes with 1TB of storage, but customers can choose whether they'd like to upgrade to 3TB, also whether they'd like their storage to be flash, pure SSD, or a new mix of two that Apple calls the "Fusion Drive."

Apple’s new Fusion Drive contains 128 GB of flash storage with 1TB or 3TB HDD, which is fused into a single volume. With access to storage, the new Fusion Drive performs almost as well as Flash, but it keeps documents significantly more secure on the HDD.

“Apple has some logic, which figures out which apps you use the most and will shift those to the SDD,” explained Apple SVP of marketing Phil Schiller, at the company's iMac announcement on Oct. 23.

The 27-inch iMac also comes with two speakers on the bottom sides of the "chin," a 720p HD FaceTime camera and dual microphones and runs on OS X Mountain Lion.

As far as connectivity goes, the new iMac has an SDXC card slot, ports for USB 3.0 and Gigabit Ethernet, as well as two Thunderbolt ports for ultra-fast connections. The 2012 iMac is also supported by the latest 802.11n Wi-Fi technology and also supports Bluetooth 4.0 (also known as Smart Bluetooth) for near-instantaneous connections with accessories and peripherals such as the Magic Mouse and Wireless Keyboard.

Apple starts selling the basic 27-inch iMac at $1,799, but for $200 more, the computer will come with some faster graphics and computing processors. Further upgrades to the computer's specs are available after that $1,999 price tag.