Dear Kelly McDaniel, In my experience working in the IT and telecommunications field, PDFs are used almost exclusively. The only time I have seen hard copies used is during eLearning courses, but that's a different context (though related) than technical documentation.
Here's why. I am writing to a highly educated, technically savvy audience. This audience is already well-informed about the field I am writing about. Consequently, they don't need to read every single chapter of a 600-page manual (yes, I have edited one of those), they only need specific pieces (i.e. modules) of information to expand or deepen their understanding of one particular aspect of the technology that I am writing about. In other words, my audience isn't using PDFs as a book but a reference guide. The key is being able to locate specific pieces of information contained in a tremendous amount of other information they don't care about. This means that a PDFs bookmarking and search capabilities are key. With those two features, the PDF meets my audience's needs regardless of what an individual member is looking for. What I find particularly interesting is the slow migration away from PDFs to a browser-based help systems. In many ways, PDFs still belong to a print-based paradigm. They have the look and feel of a manual/book, with the corresponding headers, footers, and pagination. These things are appropriate if you are creating a hard copy but its increasingly hard for me to see the justification for these manual-like attributes with PDFs that are viewed solely on a computer screen. If a user only views a PDF on a computer screen, then they generally don't care about pagination. Why would they? They have context searchable help, book marks, and hyperlinks. Furthermore, why are PDFs constrained by the dimensions of a physical piece of paper? If you have a computer screen, your dimensions are much more fungible. That's why I believe systems such as Adobe AIR applications are going to become the primary publication method in the technical communications field. In the cases, where hard copies and PDFs are still appropriate (and they still will be), I believe XML languages will function as translators to simultaneously output content to both online help systems and PDFs (I believe DITA is able to do something along these lines). -- Sincerely, Joseph Lorenzini