The NuMount Pro from Other World Computing is desk and wall mounting solution for Apple's iMac and LED displays. The mount can support up to a 27-inch display and current is supported on all recent models except for the 2012 iMac, which uses a slightly different connection.
The NuMount can be mounted either directly through a desk or with a clamp. That is all included in a kit for $189, or as a wall mount for $159. The NuMount is available now.