This is the 27-inch iMac. It's available for preorder today at configurations starting at $1,799, and begins shipping in December. The 21.5-inch iMac is available online and in stores today starting at $1,299.
The jack pack includes four USB 3.0 ports, two Thunderbolt ports, a Gigabit Ethernet jack, a headphone jack, and an SDXC card slot. But their location -- on the iMac's backside -- isn't convenient for fast cable or drive swaps.
Hidden under that bulge is a third-generation "Ivy Bridge" Intel CPU (Core i5 or Core i7), an Nvidia GeForce graphics card (GT 640M to GTX 680MX), and 1TB to 3TB of storage (with a Fusion Drive or flash storage options as well).