Apple has introduced a new line of iMacs, its eighth generation of what it's now calling its "flagship desktop line." Although broadly similar in design to its predecessor, the big departure is its thickness -- the new iMac is 5 mm thin at its edge. Part of how Apple got the iMac that thin is that it ditched the optical drive from the iMac. The display is laminated directly to the glass, similarly to how the iPhone and MacBook Pro with Retina display LCDs are built.
The 27-inch display resolution is 2,560 x 1,440, while the 21-inch is 1,920 x 1,080. Looks like you'll have to wait a while for Retina displays on the iMac. It comes with a 720p FaceTime HD camera, Core i5 or i7 processors, 768 GB of flash memory or 3 TB HDD, and up to 32 GB of RAM. There are four USB 3.0 ports and two Thunderbolt ports -- Firewire is gone.
With the iMac, Apple has introduced a Fusion Drive -- a hybrid of a 128 GB flash drive and 1 TB or 3 TB HDD. They're fused into a single logical volume, with the OS and pre-installed applications living on the flash drive. The OS dynamically decides whether apps are stored on the SSD or hard drive depending on your usage patterns in order to optimize performance.
The base model 21-inch iMac starts at US$1299 and ships in November, while the base 27-inch starts at $1799 and ships in December.