Qt 4.7 beta and Qt Creator 2.0 beta
Qt 4.7's most important addition is Qt Quick (Qt User Interface Creation Kit), a "high-level UI technology that allows developers and UI designers to work together to create animated, touch-enabled UIs and lightweight applications". It includes QML (Qt Meta-Object Language - a declarative language), new tools in the Qt Creator IDE (including a visual editor that lets designers and developers work on the same code in an iterative approach) and QtDeclarative (a new Qt module, which enables a declarative programming approach).
Qt 4.7 also includes an update to the Qt WebKit component giving greater stability and better performance. The new version is also the first released to be controlled by the Qt Continuous Integration System, which controls the process of merging new features into Qt. It is designed to increase stability and speed up release timelines. This will be important as Qt continues to evolve.
Qt Quick promotional shot
The betas are available under the commercial Technology Preview license and GNU LGPL version 2.1. More information of Qt 4.7 and Qt Creator 2.0 is available on the Qt website and in these two Qt Labs blog posts: Qt 4.7 beta 1 and Qt Creator 2.0.
Last week Nokia announced the Nokia Qt SDK (beta). This may be more appropriate toolkit / download if you are only looking at Qt for Symbian and Maemo development.
Smart Installer for Symbian
The Smart Installer for Symbian makes it easier to deploy Qt applications to Symbian phones, especially on existing phones that do not have the Qt libraries installed (Qt only becomes standard in Symbian^3). With Smart Installer, developers do not have to worry about including Qt or its dependencies on sis files with their application. Nor do they need to educate users about installing an extra file or checking for Qt library-related install issues.
Developers can package their Symbian Qt applications using the Smart Installer. When a user installs a .sis file (either directly or from a distribution point like Ovi Store) the Smart Installer component will check what dependencies are required (e.g. Qt, Qt Webkit, Open C) and, if necessary, go online, download and install them. The key benefit is that it ensures phones get an up to date version of Qt and its dependencies (ensuring applications work optimally); it also significantly reduces the file size of sis file because it is no longer necessary to included the dependencies with the sis file.
Beta 2 has better error handling, more robust downloads in poor network conditions, and a smoother UI flow (reduced number of prompts).
Here's a short video demonstrating the installation process on a phone:
More information is available on the Qt website and this Qt Labs blog post.