I recently wrote a book on InfoPath 2007. What I find most amazing about the book is that it's evangelizing InfoPath. I've shown a number of developers the book, and when they read the description, their reaction is "wow, InfoPath sounds cool - I should check it out."
How is it possible that a member of MS Office that's four years old has almost no mindshare?
I don't know the answer - I'd be interested to hear suggestions on how to get the word out to more users and developers.