Can I Mount The New (2012) iMac?
The new 2012 iMac is not compatible with the VESA Mount Adapter Kit. The VESA is usually recommended for Apple products like the iMac or Thunderbolt Display, but for whatever reason it does not support the new iMac.
UPDATE: You can now purchase an iMac with a special VESA mount for an extra $40 via the Apple Store. This iMac will not come with a stand, however, so you will have to commit to using the mount.