All expansion for Summer 2011 has been announced, and the route would not operate during the winter. At a guess if Belfast gets an -800 based then the earliest would be 2012 for Larnaca.
Out of any of the Cyrpiot routes I would expect Paphos over Larnaca as it is much higher yielding and is used by a lot of ex pats living in the south west of the Island compared to Larnaca which is primarily holiday makers going to Aiya Napa.