Photo Pixelizer allows you to easily share pictures with sensitive details, such as faces, unwanted advertising or brands, etc., by covering these details.
Sensitive areas can be covered with solid color and a professional looking pixilate effect. The "anonymized" pictures can be directly uploaded to Facebook, Flickr, Picasa, and Twitter, or just saved to the photo gallery.

More infos: http://www.tequnique.com/pixelate