I own a Kindle 2 and I have also pulled up programming books on the Nook.<p>They both suck for this application.  Because their screen size is smaller than the page of the PDFs, you are left with zooming in and out (a feature which is new to the Kindle).  This however leaves something to be desired as far as the reading experience goes.<p>My coworker owns a Kindle DX and it does much, much better at rendering technical PDFs and or technical books.<p>I also think the iPad will be very good at reading technical books as well.  Their diagrams and code snippets will render beautifully and zooming is an altogether different experience (much more enjoyable).<p>So, I would definitely go with either the DX or hold out for the iPad.