If you saw my previous post on getting started with QT, you might be starting down the same path I was, and beginning to learn QT through trial and error. The links I provided in that post suggest starting with the book C++ GUI Programming with Qt 3 (ISBN 0-13-124072-2). It turns out the book is available online.
If instead of viewing the version 3.3 documentation pages, but instead visited those for version 4.1, the book is available in PDF format. I've begun reading it, and am thus far enjoying the book. It starts off with a little history, which nicely puts things in perspective.
Enough chit chat? Here's the pertinent links: