Первоисточник

Qt Creator 1.2 introduces a broad set of new features and improvements based on user feedback. Of particular interest to Windows developers is new support for debugging applications using the Microsoft Visual Studio tool chain. For an overview of what's new in Qt Creator 1.2, visit http://qt.gitorious.org/qt-creator/qt-creator/commits/1.2 or review the changes file at: http://www.qtsoftware.com/developer/changes/changes-qtcreator-1.2.

Особенно интересным среди изменений выглядит экпериментальная поддержка компиляторов от микрософт

Qt 4.5.2 includes bugfixes and optimizations made since the release of Qt 4.5.1. For detailed information, please consult the changes-4.5.2 file found in the packages, or browse the information contained in the Developer Zone at: http://www.qtsoftware.com/developer/changes/changes-4.5.2.

Both of the releases are available in a new build of the Qt SDK (Build 2009.3). The Qt SDK contains everything needed to begin cross-platform development with Qt, and is freely available for download at http://www.qtsoftware.com/downloads.