According to the Topaz developer[1], it was cracked over a year ago; apparently the Topaz algorithm was, like .azw before it, trivially bypassed by prodding at the KindleForPC application.
Furthermore, Topaz is a rarely-used specialty format. It has existed for at least three years (based on the blog's date and text), but AZW/mobi continues to be by far the dominant format for purchased Kindle books.
