Hello,
Just to clarify a few points -
1. The term Palestinian-Arabs refers to people who identify themselves as part of the Palestinian People, but they hold various nationalities. Many of them are Israeli citizens, so they can arrive at Haifa just as any other Israeli (and like other Israelis, they might register at the last moment, since they don't need accommodations). Those who live in East Jerusalem are not necessarily Israeli nationals, but they have free access to any place in Israel (they hold Israeli IDs, which are more-or-less like Green Cards in the US). Those living in Jordan and have Jordanian nationality should obtain visa from the Israeli embassy in Amman. Those who live in the West Bank and are under the jurisdiction of the Palestinian Authority enter Israel with their Palestinian internal ID and a permit which the PA office obtain for them from the Israeli authorities (so they need to file the request at the local PA office). Many of them have a permanent permit - these are usually WB residents who work in Israel. The main problem is with residents of the Gaza Strip, due to the very delicate political situation there. It is possible to obtain permits for them too, but it requires some coordinations with the relevant authorities. I personally made some phone calls, and received detailed information about how to start the process, but unfortunately, I received no information about people from Gaza who actually filed requests to enter Israel for attending Wikimania.
2. Palestinians have good access to Internet. Currently, the Palestinian ISPs relies on the Israeli infrastructure, so it might seem as if they connect from Israel, though in many cases I saw Palestinian Territories as the designation of location for people connecting from the WB and Gaza. That said, Wikipedia is not very popular among Palestinians, as far as I can judge. Wikipedia and Wikimedia projects are extremely popular among Hebrew-speaking Israelis, but Arabic-speaking Israelis and Palestinians in the WB and Gaza are much more into writing blogs, posting comments in various Arabic-speaking web-forums etc. When I was interviewed in Arabic about Wikipedia, the Palestinian person who was interviewed with me was not a Wikipedian, but rather the head of a Palestinian bloggers' union.
3. I talked with some Egyptians who considered coming to Haifa. It wouldn't be fair to reveal information given to me in private conversations, but I can say that the current situation in Egypt poses unexpected difficulties to Egyptians who wish to visit Israel. The Israeli embassy in Cairo and the consulate in Alexandria work normally, and visa procedures have not changed, and yet being listed as someone who crossed the border to Israel is something many of those I've talked with prefer to avoid at the current state of affairs. I'm afraid this is beyond the control of any of us, and it is an unexpected development of the past five months or so.
Dror K