The blog post can be read in full at BlogSpot, but it basically comes down to leveraging QtComponents / QML / Qt Scene Graph to allow every paint operation to be accelerated on the graphics processor by using OpenGL. Part of wanting to do this is because some components (like QGraphicsView) are not as fast as they could be and there's just much room for improvement. All of this work though would result in a new library (libplasma2) that would be source and binary incompatible with the current Plasma library used by KDE SC 4.x. Nearly everything would need to be ported over to QML as part of this endeavor.
Let's just hope by the time this KDE Plasma overhaul is complete that the open-source graphics drivers have been bettered and that LLVMpipe is in a fast and modestly usable state for everyone else lacking GPU support.