Review on HumanCentric VESA Mount Adapter for Apple Cinema Displays - Compatible with 20 inch and 23 inch Models, Replaces Apple M9649G/A, Patented and Effective by Jeremy Taylor

FYI I can confirm YES, this works with 30" cinema screens and 20" and 23" displays. Just use the included long screws from the stand. This adapter fits INSIDE the display mount because it's so large instead of attaching to the outside, but it's exactly the same as the original Apple VESA mount adapter. The packaging even says it works with 20, 23 and 30 inch cinema displays. Just reuse the existing screws and you're good to go. Good adapter, my review reflects that the long screws are not included and the product description is incorrect.