I personally contacted people from the Palestinian community of Israel and spread the word in the meetings I had with Palestinians from the West Bank. People showed some interest, some of them were not too acquainted with Wikipedia and asked questions, but apparently it didn't bring them to the registration page. Furthermore, I was responsible to the translation of the whole site into Arabic, including the landing page and registration page. This means that Wikimania in Haifa pops up in Arabic in Google or any other search engines. I also translated the press release about the event and I know it was sent to the major Arabic-language newspapers in the country.
That said, I am more than willing to contact any person in the West Bank in order to promote Palestinian participation. Many Palestinians have permanent entry permits into Israel, so they can reach Haifa easily, and there are many with Jerusalemite residency, who also don't need any bureaucratic arrangements. In case some bureaucracy is required, I do my best effort, as I have the necessary phone numbers at hand.
It is important to note that we encountered this year unprecedented attempts to discourage people, particularly Arab people, from coming to the event. I don't blame anyone, and I respect the freedom of speech of everybody, but it is very hard to promote an event among Arabic-speaking people, when there are FaceBook groups and blogs, some of them initiated by Wikipedians, calling upon Arab people not to attend, and even spreading false information.
Dror K