Since upgrade to Lubuntu 12.10, I can't publish photos to Facebook, as the system is now integrated with "Online Accounts", but these can't be configured. There's no relevant entry in the configuration center.
Close shotwell (all aplication related, like control-center)
Use the shell:
Change the line:
Save and quit. Then, in the shell wirte this:
Add your accounts, open shotwell and export your photos :)