The guys over at SamMobile were lucky enough to get their hands on an early preview build of Android 5.0 Lollipop on the Samsung Galaxy S5, as you can see in their video below. The operating system has definitely not reached its final form yet, but the progress is very clear.
As you can see, Samsung's signature TouchWiz style still reigns supreme, but touches of Android's new Material Design are splashed in here and there.
The Messages, Music, and Settings apps all have Android 5.0's color-matching status bar activated already, and Lollipop system animations are present throughout the OS.
SamMobile expects this new version of Samsung's stock firmware to be ready some time in December, but factoring in carrier modifications, an update shouldn't be expected until early 2015.