Keir Thomas, the author of Ubuntu Pocket Guide and Reference, provided some numbers on the Ubuntu News Team list:

I thought I’d provide a quick update on the book.

Since the website went live about 48 hours ago, the PDF Edition has been downloaded over 100,000 times. This makes it the world’s most widely-read Ubuntu book (at least according to Nielsen book-sale
figures), and possibly the most widely read Linux book of all time

The best thing, however, is that I might have helped convert some people to Ubuntu. I think the book might have pushed some people over the edge — they’ve been thinking about adopting Linux, and my book gives them the reason to do so. I’ve read quite a few comments here and there to this effect. Although I wrote the book primarily to make a living, I think this is just great. I couldn’t be happier. The print edition of the book’s doing really well at Amazon.com, by the way, and is probably the best-selling Ubuntu book right now.

Thank you all for your kind comments, and support.

Cheers

Keir

Awesome job, Keir!