The plugin : https://dl.dropbox.com/u/1412774/FaceDetectDemo2/pode_facedetect.1.1.zip
Here's a new behavior, allowing you to detect a face in the Sprite it's attached to. You can get the (X,Y) of the found face, its width and height, the confidence (only the first found face is reported).
As you can see in the screenshot, there's also the possibility to retrieve a cropped version of the found face (you can give the margin you want to add around the original found face, since the bounding box can be a bit "tight"). The cropped image is given as a base64 string that you can load in a regular Sprite.
The whole thing was made using the helpful jQuery FaceDetection plugin : http://facedetection.jaysalvat.com/
The demo : https://dl.dropbox.com/u/1412774/FaceDetectDemo/index.html
The plugin : https://dl.dropbox.com/u/1412774/FaceDetectDemo/pode_facedetect.1.0.zip
The .capx : https://dl.dropbox.com/u/1412774/FaceDetectDemo/FaceDetectDemo.capx
I'm planning to add several face detection in the same image in a future release.