You can arm the new iMac, provided you mean the supersexy 24-inch model. For some reason, Apple only sells a VESA-mount adapter for the largest of the new iMacs. Just make sure you get the right adapter, as Apple also made an adapter for the previous-generation iMac. You want part number MB060G/A (unless you want an arm for last year’s model, MA473G/A).
VESA Adapter Kit for 17-inch, 20-inch, and New Aluminum iMac 20"
Submitted by Scott Powers (not verified) on Mon, 2008-02-18 19:08
imacmount.com provides a VESA-mount adapter kit for 17" and 20" Apple iMac; including the all new Aluminum iMac 20". This solution attaches to the stand of the iMac and doesn't require any modification to be made to your iMac computer. Very easy to use, check it out.