A few weeks ago Pocketnow.com had a video showing bounce back was removed in the newest builds of WM 6.5.1, well its back with a vengeance. Will installing a new application today, I noticed that my phone had a weird effect when I scrolled to the top of the screen. After much looking at, I noticed it is the new bounce back effect, and it is a lot better and looks nicer. It gives you a 3 stop bounce, First bounce is pretty weak, second is weaker and third is weak enough for it to stop. If you have a phone with build 23504 or higher, I would give it a try, because it looks nice and only works in curtain menus and only if you use enough force.
Here is a video I made to demo this effect.