The new developer preview of Android 5.0 includes one tweak I'm sure everyone will be happy about—the dismiss all button has returned to the notification shade. I don't think anyone seriously considered the possibility that it would be gone forever, but it's good to see it back.
The new dismiss all button has shifted from the top of the shade (in KitKat) to the bottom. That actually makes a lot of sense as it's closer to your fingers after you've pulled open the shade. It does what you'd expect when you tap it, but still, yay.