Re: Sidekick
Actually, even though the content of the two are the same, they are considered seperate products and are paid for and treated accordingly. One does not have any right to a PDF copy of a physical book that you own any more than you have the right to a paperback version of a hardback that you own.
Furthermore, you are not allowed to make an electronic copy of a physical book, even for back-up purposes and, if I recall correctly, PDFs do not qualify as 'software' and thus aren't eligible for back-up privileges, either. Consider this: lately, there's been a bunch of noise about whether it was legal to rip a CD for personal use on a portable media player. I think some are claiming that the Fair Use allowance for CDs is meant only for making a duplicate physical CD and not an electronic copy.
Finally, I doubt any company that sells both PDF and physical versions of a book is going to allow you to make your own PDFs, even if you ask nicely. As I wrote above, a PDF of a book is an indepedent product which can, and should, be purchased seperately. Sure, it'd be nice if you could buy a physical book and get a PDF for free but it generally doesn't work that way. On the other hand, some companies, like Apress, allow you to buy a PDF versions of their books at a discounted price if you own a physical copy, an offer which I have taken advantage of several times.
I'm not a lawyer. I just play one on the Internet.