A developer by the handle xsmile711 has ported a version of the Android L lockscreen that will work on most Android 4.0+ devices, rooted or not.
The application requires you to grant it notification access and disable the default lockscreen, but once that’s done you have what appears to be a fully functioning next-generation lockscreen.
You can define directions to swipe on the screen to launch various applications, set 12 or 24 hour format, blacklist individual apps from showing on the lockscreen along with some premium-only features such as blurring your wallpaper on the lockscreen.
The Android L Lockscreen app appears to be a little short on actual security unless you upgrade to the premium version ($1.70), and if you’re paranoid, the access requirements should send you running until Android L is actually available on your system or a completely open source version is available. But it’s interesting to get your hands on to see what’s coming.
Unfortunately it’s been a slow notification day for me with mostly app updates and spam appearing in my notifications, but the ability to launch apps to handle notifications from the lockscreen could be very useful, or terrible if you’ve got a grabby little young one around your phone.
If you want to play around before setting it as your lockscreen, there’s also a preview mode (which is seen in the picture here), but there’s really not too much that appears to be doable with it.
There’s a way to disable the nav bar, but it seems a bit buggy on the HTC One M8 (disappearing and reappearing at random). The app also takes a decent chunk of memory so older devices might get bogged down with the application. It’s not quite ready for prime time, but the author states it’s in beta and it’s being updated on a fairly regular basis, so if there’s a problem now, there’s a good chance it’ll be fixed before the actual Android L lockscreen is available for your device.