Mr. doob first made it with Flash and Papervision 2.0. Then when he got an Android phone, he ported his code to Java+OpenGL ES, and published the result in the Market. People were loving the application, but they still wanted more! Specifically, they wanted a live wallpaper.
Not only it is now a live wallpaper, but it also includes the previous application so that you can move the time around and generally toy with it, and you can also configure the appearance in order to suit your preferences (background color, 12/24H).
I've been in charge of morphing and refactoring the clock code so that it would work in several different contexts (the main activity, i.e. the application; the wallpaper itself, and the Settings activity); I've also spent lots of hours making sure the application is as optimal as it can be, so we don't use your battery unless needed, and you don't get constant garbage collections; therefore the output is always smoooooooth.
Since this involved more than a single, isolated activity in a single, isolated application, it's really been quite a learning experience; and now I know an awful lot more about the life cycle of activities, services, OpenGL contexts and what not. This will surely prove useful in the future, so stay tuned for more 60fps projects ;-)