First up, I think this book works well. I know some purists have been debating whether or not this is worth the time, but it does have some funny ideas and great lines.
There are quite a few good parodies out now. Neil Gaiman and the Mighty Boosh are producing close take offs, and The Chap is a seriously funny magazine. "Sherlock Holmes and the Underpants of Death" is being well received, and as ever take offs of new films are going down well.
I think the success of this book is something of a phenomenon, however. Does anyone think it'll last?