The improvements in Qt 4.6 can be summed up as more platforms, more eye candy, more fingers, and more horsepower. Qt 4.6 adds support for the Symbian platform, and obviously also gains support for Mac OS X 10.6 Snow Leopard and Windows 7. In addition, community support is available for the real-time operatig systems QNX and VxWorks. Meamo 5 is on the way, with its second technology preview released today.
Eye candy-wise, Qt 4.6 gets the Animation Framework, which includes "intuitive state machine functionality", as well as new graphical effects such as opacity, drop shadows, glow, and filtering. Qt 4.6 also comes with multitouch support, providing the ability to, among other things, flick and scroll kinetically.
As far as performance goes, the Qt GraphicsView rendering algorithm has been rewritten, but 4.6 also receives a new OpenGL paint engine, WebKit, 2D vector graphic support using OpenVG, and new DirectFB support.
"Qt 4.6 marks an exciting time for developers, regardless of their target form factor or platform," said Sebastian Nyström, Vice President, Application Services and Frameworks at Nokia, "Developers can easily create visually appealing and web-connected applications for desktops or devices, including targeting the hundreds of millions of Symbian and Maemo-based devices. The community will enjoy using Qt's intuitive programming interface to quickly create powerful, appealing applications."
You can get Qt from its website.