The screenshot you see below is claimed to be the first showing Android 5.0.2 Lollipop on the original Xperia Z (C6603). It shows that the handset is running on the 3.4 kernel and with a build number starting with 10.6.A.0. This would fit given the currently released firmware with build 10.5.1.A.0.292 i.e. the move from 10.5 to 10.6. Obviously the screenshot could be a fake, but hopefully it indicates the Lollipop update for older Xperia Z series is just around the corner.