Yesterday I updated mine with this: http://harmattan-dev.nokia.com/release/N950-39-5/ I tought that it would be the safest way, since the device had a firmware that was older than the previous of 39-5. With Kubuntu 10.04 update worked like a charm with the instructions linked above. Note, however that One Click Flasher will erase everything, so backup if you already have some important data on device! I'm curious about the leaked firmware, too. Any comments about it would be appreciated much!