The following links will give you a starting point for learning about Qt application development on mobile devices.
Getting started
Getting started with Qt on Nokia devices (developer.nokia.com) — is a very good place to start.
Qt SDK (developer.nokia.com) — the toolset you need to go from application concept to a fully tested, ready to deploy application.
Qt learning materials (developer.nokia.com) — download the latest self-learning packages and more.
Qt code examples (developer.nokia.com) — example applications developed and optimised for mobile devices.
Mobile hands-on labs / Qt (developer.nokia.com) — learning by doing, Qt online hands-on tutorials with source codes.
More detailed information about Qt on Symbian devices
Qt & Symbian Platform Security (developer.nokia.com) — an introduction to Symbian's security model and how it works with Qt.
Deploying a Qt Application (developer.nokia.com) — how to get your Qt application on other Symbian devices.
Qt & Application Signing (developer.nokia.com) — how to digitally sign your application using Qt Creator or qmake.
Creating Energy Efficient Apps Using Qt (developer.nokia.com) — how to create power efficient Qt code for use on Symbian devices.
Qt's platform notes for Symbian (doc.qt.nokia.com) — describes the status of the port of Qt 4.6 to the Symbian platform.
Qt and Symbian C++ together (developer.nokia.com) — provides technical details about how to make Qt and Symbian C++ cooperate
qmake extensions for Symbian (doc.qt.nokia.com) — Qt's qmake tool has some Symbian-specific extensions.
Smart installer for Symbian (developer.nokia.com) — a tool to package with an application installation file. The tool checks the version of Qt on the device and downloads the latest version of Qt if necessary.
Qt development on MeeGo 1.2 Harmattan devices
MeeGo 1.2 Harmattan Developer Library (developer.nokia.com) — in addition to Qt development content, provides information on platform specific APIs.
Nokia N9 UX Guidelines (developer.nokia.com) — provides guidelines for building great looking and user-friendly user interfaces with the MeeGo 1.2 Harmattan style.
Support
Qt Developer Zone (qt.nokia.com) — Qt's main page for developers.
Qt's main support page (qt.nokia.com) — official support options from Qt.
Nokia Developer Qt wiki (developer.nokia.com) — wiki articles about Qt on Symbian and MeeGo devices
Qt discussion board (developer.nokia.com) — find help from other developers using Qt on Symbian devices.
Forum Nokia knowledge base (developer.nokia.com) — code snippets, technical solutions, and known issues.
Qt Roadmap (qt.nokia.com) — information about the latest updates to Qt
Qt Add-Ons (qt.nokia.com) — information about the latest mobile-related Qt APIs
Qt books
C++ GUI Programming with Qt 4, Second Edition (qt.nokia.com) — the official Qt book.
C++ GUI Programming with Qt 4, First Edition (www.qtrac.eu) — this older version of the official Qt book is available online.
Qt for Symbian (eu.wiley.com) — goes into depth about how Qt works on the Symbian platform.