A few of my persistent search feeds for "Hacking RSS and Atom" have started returning results for my book in PDF form on BitTorrent trackers and filesharing networks.
I've hit the big time now!
Though, you know, the cool kids buy the dead tree edition. You want to be cool, right? Looks like there's a promotion going on over at Barnes & Noble right now...
You know ebooks have failed when you see how little they hit the filesharing networks... The only authors you can consistently find are Stephen King and the GoF. The fact that yours has managed to get there is definately a sign that your popularity is indeed growing.
Sad thing about current version is that it's not yet a "processed book", i.e. you can't use hyperlinks, index or search features as they should be used. But it leaves a hope that at some point some pirate group will take that consideration into account and OCR/republish the release.
Interesting thing is that released PDFs are mostly of high quality and thus most probably "couriered" right from the publisher's production facilities or electronic shops. And this allows us to see, how each of the publishers relates to e-books in general.
I.e., big new releases of O'Reilly (e.g Project Management) are reworked as fully developed CHM-ebooks with indexes, TOC and hyperlinks, smaller ones are PDF with text (smaller size than full-page renders, copy-able text and possibility to do search for strings).
And very rare releases are in scanned PDF format, which usually means that no real electronic version existed before (or it never got to public).