Krita developers have been working on improving the rendering quality and perforamcne of the KDE application. One of the major Krita 2.8 features is a reworked OpenGL engine where with the "High Quality Filtering Mode" they are now using GL3. Noted as being of real benefit with the new GL code is better quality on zoomed-out images, better performance with high-resolution images, and the engine is more efficient and responsive. Krita has long had support for using OpenGL/GLSL but with this forthcoming release there's many improvements and now the OpenGL 3.0 hardware/driver requirement.
Krit 2.8 also has benefits of a dynamic outline in hover mode, refactored tool mode shortcuts, and enhancements to the color picking shortcuts.
Dmitry Kazakov has been working on the new high-quality scaling algorithm and other improvements to the KDE paintaing program. Dmitry blogged about the Krita 2.8 work this morning and more details can be found in a blog post earlier in the month at Krita.org.