Processing a batch of raw files using the original Camera Raw plug-in (CRI) was possible, but limited by the fact that it wasn't practical to apply individual settings to each image file to be processed. You had to create a set of parameters that were then applied to every image in the batch. So the best you could do was organise raw files into groups in separate folders and have multiple batch runs. That has changed with the CS Camera Raw plug-in (CRII).
Photoshop's technical architecture apparently doesn't allow for the background conversion of images as, for example, Capture One DLSR can do. However, CRII settings are saved as metadata, which can be seen in the Metadata tab:
This means that you can specify all the conversion settings for each raw file in a batch, save these settings and then subsequently batch convert the images.
How do you save individual settings? Simple! In the File Browser, double-click on a raw file file so that the CRII window opens. Tweak all the sliders (I counted 21 - of course, you don't have to use them all 
) to make your picture beautiful, then instead of clicking [OK], which would convert the image, press and hold the
Click this and the raw files closes, your CRII settings are saved to the metadata file and, after a moment or two the thumbnail and preview are refreshed to show the effect of your adjustments.
Repeat the process for each of the raw files you are planning to convert - you can select multiple files at the start and the next will open as the previous file is updated - and you are ready to begin batch conversion. I'm sure there are several different ways to batch process, but this is my preferred method - guaranteed to work and offers a lot of flexibility. I've described the approach before, so I won't go into detail how to create this action, except to mention that you should change Settings in Camera Raw to "Selected Image" and not "Camera Default" (and thank Thomas Knoll - yes, the Thomas Knoll - for pointing this out):