I'm really starting to like the recent trend towards publishers making books available in both PDF and Dead Tree form. It's a refreshing change of pace when compared to the regular DRM ladden crap we get from the entertainment industry, I'm glad that at least the technical book publishers appear to be a reasonable bunch with regard to such things.
The way it's worked is simple, you order the book from the publisher like you normally would, and for either slightly more or the same amount you would normally spend in a bookstore you get the hard copy shipped to you and a personalized PDF (with some kind of "this pdf prepared for <your name here>" thing on each page) prepared so you can download it immediately.
For technical books this is fantastic. If I order a tech book online I'm probably interested in it right now, so the PDF means I can get some instant gratification, which is a big plus. Then, later on I get the text version which, lets face it, is much nicer to read. In the long run though, I'll always have the PDF on my laptop so I can look something up if/when I don't happen to have the hard copy on me.
As for the DRM issue, I like to think that the personalization of the PDF is a nice way to keep people from passing them around on file sharing systems, although it's possible that's just me being overly naive. Time will tell I suppose.
In any event, I'm pleased with the few books I've purchased in this manner so far, and I plan on doing so again in the future if I'm given the opportunity.
Now back to reading about Lucene...