It took Apple months to catch up with the demand for its most recent iMacs, but now they’re finally in stock. So what’s next? VESA mount support. Neither the 21.5” or 27” models can actually be mounted when purchased as is—a limitation that affected the prior 21.5” iMac as well. To address that issue, Apple has today released both 21.5” and 27” iMacs with Built-in VESA Mount Adapter (Late 2012) ($1339-$2039). You can’t just buy a separate Apple VESA mount adapter; instead, you buy the Mac with the adapter pre-attached.
Specs-wise, these iMacs are exactly the same as the ones you would buy without the adapters—the only difference is the $40 premium for the adapter itself. Considering Apple sells standalone adapters for older computers and displays for $39, the price is fair; you just have to be prepared to provide your own stand or mount.