Update: With striking proof that I'm dense and a Developer of Little Brain, Andrew points out that the results are sorted by date added. :- P
On at least one torrent search site, our book is the #2 item when you search for WPF. Not searching for "WPF book", just "WPF". Rock on.
I have an alert setup that notifies me every time the book title is indexed on Google. There's an new pirating (free books!) link about once a week.
If only I had a positive review for each site! :-)