I just talked to a nice lady who works at Olympic air about the summer flights to Naxos (A month before I was told that it would be possible to book a flight to/from Naxos in January 2012. Also, I bought my summer 2011 flight more than half a year in advance.).
She told me that the situation changed significantly in 2012.
At the moment it is not even clear which company will take care of the POS flights (and nobody knows about the frequency of these flights yet). She advised me to call again at the end of February.Edited: 25 January 2012, 11:39