As part of my Windows Phone 7 theme for the HD2, I have released the lockscreen of the upcoming version as a stand-alone app.
This application will run on any WVGA device.
This app smoothly slides down over the currently displayed screen, and then you can "peek" at what's under it. To unlock, start at the bottom of the screen and slide up. This can be pinned to your homescreen, or set as a button.
It's a first-release, but I want to make sure all the kinks are out of it before including it in my Windows Phone 7 theme (release TBD).
Download, copy, and install to your device.
Changing the wallpaper
You can change the background of the lockscreen by placing a file on the root of your device and naming it lockscreen_image.jpg ("\\lockscreen_image.jpg"). The file must be in WVGA resolution and JPG format.
Any questions, comments, or trouble, let me know
Update Jan 2012: This project hasn't been touched in years, but if you still want it, this download link should work: