July 22, 2011:
In Gaza, Hamas recently issued warning to those playing online games. Israel has recruiters in these games, who pass themselves off as Arabs, and troll for likely candidates to be informants for Israel. Israel offers cash, goods or favors for information. There are always takers. Hamas is desperate to halt this sort of thing.
Hamas has always known about Israeli informant network in Gaza, and the difficulty in eliminating it or, more realistically, doing some damage to it. The key to Israeli success in dealing with Palestinian terrorists has always been an informant network within the Palestinian community. Many of these Palestinian informants are doing it for the money. Israelis pay for information. They also use other inducements (help with the bureaucracy, medical care, etc). If that fails, they use blackmail and threats. Palestinian terrorist organizations have been unsuccessful in their attempts to shut down the informant networks, and many innocent Palestinians have died simply because they were falsely accused of being informants.
In addition, the Israelis gain a lot of information via electronic intelligence work and UAVs that are constantly in the air over Gaza. Israel seeks to make the terrorists think that it's the gadgets, not informants, gathering the information. To the Israelis, inducing paranoia among the Palestinians is seen as a successful weapon. All this has helped keep the terrorists out of Israel for over six years now, something no one thought was possible.
Israel also has hundreds of police and military operatives who can pass as Arabs. That's because the families of these Israelis came from Arab countries shortly after Israel was founded in 1947. These Israelis speak fluent Arabic (with a Palestinian accent), in addition to their Arab appearance. These agents dress as Palestinians and enter Palestinian areas to recruit and run Palestinian informants. At least in the West Bank. In Gaza, the Israelis use pro-Fatah (the rival group that runs the West Bank) Palestinians. At least a third of the Gaza population is still pro-Fatah, and continued Hamas pressure has not changed that.
Meanwhile, telecommunications hacking has become a major part of Israeli espionage over the last decade, which accounts for more "Israeli spies" being caught. Israel recruits people in Arab telecom companies, a lot of people. Some get caught. But Israel has been able to hack into cell phone systems and monitor the Internet in Arab countries. Information, for Israel, is a matter of survival.