Android 4.4 KitKat can be ported to the Nexus One
Thanks to the talent at XDA Developers that managed to hack together a custom Android 4.4 ROM, the original Nexus is lives on, even though official support for the device stopped after Android 2.3 Gingerbread.
This new 4.4 ROM is not the whole KitKat experience, and like many custom software packages, it is not without its flaws. There is no screenshot functionality and it is possible to get stuck in a bootloop error.
Because of the size the overall KitKat file, some parts of the package were removed altogether. The camera is not 100%, and features like Video Editor, Calendar, the email client were removed from the ROM. Only the newest sounds were included. Some of these removed items can be reinstalled except for the video editor which is simply too big. It is KitKat though, so if you still have a Nexus One hanging out somewhere, check out the source links to give this ROM a try.
sources: XDA Developers (1, 2) via Engadget