The Snapshots Tab
Before Camera Raw 5.2, saving alternate renderings of an image was somewhat clumsy. For example, if you wanted to save both color and black-and-white versions of an image, you had to copy the image itself or save a separate settings file for each version. Copying the entire image is an inefficient use of disk space, and saving a settings file wasn't ideal because it wasn't automatically associated with the image—you had to give the settings file an easily identifiable filename, and fish around for it on disk or on the single settings menu provided for all of your images.
In Camera Raw 5.2, Adobe added snapshots, a simple solution already implemented in Lightroom. A snapshot is a saved state of all Camera Raw settings for an image. You can use snapshots like an image history so that you can return to earlier points in the editing process, or to save alternate versions of the same image such as different crops, optimizations for different color spaces, or the black-and-white and color renderings mentioned earlier.
You might ask, "How is a snapshot different from the existing presets feature?" Presets are not image-specific, which makes them difficult to use for tracking image versions. A snapshot is saved only with a specific image, so as you load different images in Camera Raw you can see each image's own list of snapshots (if they contain them).
Another difference is that a snapshot always records the settings for every Camera Raw option in the main Camera Raw window. With presets, you can decide to include just a subset of Camera Raw settings.