Nokia has just announced the first technology preview release of Qt 4.8 to the open-source community. Qt 4.8 carries a variety of performance improvements, particularly for file-system performance, but the big feature of the Qt 4.8 release is Qt Lighthouse.
Qt Lighthouse is the new platform abstraction layer designed to make porting Qt to new platforms and graphics sub-systems much easier. Qt Lighthouse is also part of the Wayland upbringing. MeeGo Tablet UX and therefore Qt is already running on Wayland.
More information regarding the Qt 4.8 Technology Preview can be found in this Nokia Labs blog posting. The official release of Qt 4.8 is expected in the second half of 2011.