Not happening for me either, cant do it OTA, which asked me to do it via the Nokia updater, which tells me I have the current software already! Probably give it a while then try again...
Also, what's the Nokia Software Update application? That some Windows application?
The most likely reason is that you have less than 57Mb in rootfs. There are loads of threads on how to clear enough space (uninstall some apps and disable repositories etc). Otherwise you can use flasher or Nokis SSU.
Did anyone doing a FOTA get stuck at a black screen after the download finished? Mine isn't responding.. that could mean it is doing something.. or something bad has happened..
what have been the FOTA experiences so far? How long did it take, for example