According to our PM it is.

He said that :

Speaking to the global forum of the Alliance of Civilisations in Vienna on Wednesday, Mr Erdogan said: “As is the case for Zionism, anti-Semitism and fascism, it is inevitable that Islamophobia be considered a crime against humanity.”

http://www.telegraph.co.uk/news/worldnews/europe/turkey/9902255/Turkeys-Recep-Tayyip-Erdogan-under-fire-for-Zionism-remarks.html

I think the question is what do we understand from the word of ´zionism´?

zionism is a word that will come wherever you drag it to. you can say that its a whatever thousand year old cultural myth or a nations source for pride, but the people who have lived in this region view it as something completely different. what the gray wolves or skull-measuring racist right-wing pro-turkic ideologies in turkey are for the people who have suffered most from them (ie leftists at 80s), thats what zionism is for the people who have suffered israels ultra racist behaviour models. for example zionism might be a way to express freedom against tyranny for an israeli person who drives on the exclusive highway in israel, but for a pragnant gazzean lady who has to go trough 12 checkpoints everytime she wants to visit the hospital zionism is a word that is in sync with tyranny itself.

and erdoğan, who have suffered a serious blow to his career with mavi marmara murder, views zionism as he has seen it from there: violent and segregating. it did bother people a lot that israel spared every other ship but not the turkish one, just to punish erdoğans harsh words for israel in davos, so erdoğan naturally uses the word in that botherful context.