Cheers !

Thanks to linuxopjemac I removed mbp-nvidia-bl-dkms and installed nvidia-bl-dkms.
And after a reboot, my function keys for screen brightness that broke during maverick upgrade are back again.

Great !!

For information:
MacBook5,1
02:00.0 VGA compatible controller: nVidia Corporation C79 [GeForce 9400M] (rev b1)
Description: Ubuntu 10.10