The planned route looks like this (via Israeligirl):
The final leg seems to be intended to be a ship from Syria to Gaza.
The group behind it is called Asian People's Solidarity for Palestine, and they claim that some of the members of the journey were injured on the Mavi Marmara, making it clear that these are not "peace activists." (Their manifesto also calls for the"right of return," showing that they are anti-Israel activists as well.)
They plan to arrive in Gaza in time for the second anniversary of Cast Lead.
I believe that Israel would regard a ship sailing from an enemy state to be an act of war, and that threat (as I recall) was what scuttled the Lebanese "women's flotilla" last summer, as they could not find a country willing to host the final part of the journey. I think it is doubtful that Syria would risk this, but it is a story that needs to be followed.
(h/t Israeligirl)
UPDATE: Commenters have noticed what I didn't - that the last sea leg of the journey is in fact to El Arish in Egypt and then an overland convoy to Gaza, similar to other convoys and something that Israel does not object to. Egypt has just as little interest in Hamas acquiring weapons as Israel does.