Straight from Nokia's Press Release:
Oslo, 19 January 2010 – Nokia today released version 4.6.1 of Qt: the cross-platform application and UI framework, and version 1.3.1 of Qt Creator: the cross-platform IDE for Qt development . Qt 4.6.1 brings improvements to developers targeting Symbian,
most notably introducing a binary compatibility guarantee as announced
with the Qt 4.6.0 release in December 2009. Both releases introduce
bug fixes and optimizations made since the Qt 4.6.0 and Qt Creator
Also released today are updates to the Qt Visual Studio Add-in and Qt Eclipse Integration, as well as an updated build of the Qt SDK. All Qt releases are available for download from http://qt.nokia.com/downloads.
Binary Compatibility Guarantee on Symbian
4.6.1 brings a binary compatibility guarantee for applications built
for the Symbian platform, as announced with the release of Qt 4.6.0.
For more information, visit http://qt.nokia.com/products/platform/symbian.
Qt Beta for Maemo 5 Also Released
A Beta of the Qt port to Maemo 5 is now available for download, testing and feedback. For more information, visit http://qt.nokia.com/developer/qt-for-maemo-developers.
For a detailed list of changes introduced with Qt 4.6.1, consult the
changes file found in the packages, or browse the information contained
in the Qt Developer Zone at: http://qt.nokia.com/developer/changes/changes-4.6.1. A detailed list of changes in Qt Creator 1.3.1 is available at: http://qt.nokia.com/developer/changes/changes-qtcreator-1.3.1.