The hacker group Anonymous has apparently jumped into the Israeli-Hamas conflict by releasing the names and personal email addresses of five thousand Israeli officials, along with a message declaring cyber war on Israel. It is Anonymous who used the term cyberwar; so this is not my interpretation of events. Additionally, but not necessarily related, the Israeli government is combatting tens of millions of cyber attacks on the country's infrastructure and government web sites.
There is no doubt that future armed conflict are going to be accompanied by a complementary cyber war strategy. What remains to be seen is how much affect non-state actors, like Anonymous, who are not parties to the conflict will influence the outcome. Let's be clear, hacktivists groups who engage in cyber warfare are in the same legal category as "enemy combatants" who ended up in Guantanamo. By engaging in cyberwar, they have become combatants, breaching the sovereignty of another nation, but without the protections that would come from working as a lawful combatant of sovereign nation at war. Like it or not, international treaty does not protect such actors in the same manner as soldiers.
As a consequence, I expect the Israelis to eventually get annoyed enough to take some action. Hacker groups are not immune from the detective work that trips up any other criminals. This year, leading members of LulzSec and Anonymous were arrested. If the Israelis snatch some members off the streets, don't expect them to announce the abductions any time soon. Further, they might be within their rights to do so, because of the lack of legal protection afforded unlawful combatants.
The Law of Armed Conflict is intended to clearly distinguish between civilians and soldiers so that civilians may be protected. Soldiers are afforded certain protections, to encourage proper treatment of prisoners of war on both sides. Civilians are also afforded protection, both in the conduct of war and when they come under occupation. By hiding in the civilian population, terrorists and hacktivists undermine the legal framework that protects civilians. In much the same way that Hamas is responsible for the deaths of Palestinians by placing rocket launchers in civilian neighborhoods, so too do groups like Anonymous damage our rights in cyber space by performing criminal acts and unlawful acts of war.