User Experience (UX) design isn't a new field. But sometimes new approaches lead to new perspectives. In this book, you'll learn how lean UX has made the whole discipline more approachable and attractive to startups, and you'll see that UX issues aren't just a quick fix, but should also address big-picture issues. Sometimes, the solution to a problem is to fix a broken UX; other times, you will need to constantly fine-tune in order to keep up with changing demands. You'll also look at wireframing alternatives, research planning and design bias.
Nice addition the Smashing's mobile book. The articles seemed to lack focus a little - sort of broad and not particularly deep (one chapter covered both UI design patterns and setting breakpoints in Xcode), but none-the-less it had some good information.
(Full disclosure: I didn't read the Windows Phone chapter, as I have no immediate plans for developing for the platform)