Of course, it was only a matter of time before the guys at XDA tinkered with the device and made a custom Android firmware for it. Senior XDA developer dhacker29 made a custom Android 4.1.2 Jelly Bean ROM for the device. The firmware uses source code from Code Aurora, which consists of vanilla Android and all specific enhancements and optimizations for Qualcomm's chipset, present in the device.
The current build of the firmware is described as stable enough for everyday use. It has a pretty long list of working features, most notably the network connectivity, camera, FM radio, GPS and location services, etc. However, there were some navigation issues, as the Nokia X comes with a single hardware button. Fortunately, the developer of the firmware released a second version, which comes with on-screen navigation buttons.
In order to flash the custom ROM to your Nokia X, you need to root it and flash a recovery tool. Google's apps, the so-called gapps package, have to be flashed as well. You can learn how to do so by following the source link.
Nokia X running Android 4.1.2. Jelly Bean
source: XDA (1), (2)