It may not have been as dramatic as the sudden toppling of an 80-year-old dictator, but the announcement on Wednesday evening of the signing of an agreement between the Fatah-dominated Palestinian Authority and Hamas was a direct development of the winds of change blowing through the Arab world.

Both sides have been intermittently negotiating for six years, but it took the revolution in Egypt and the current uprising in Syria finally to push them together.

The agreement is essentially identical to the document that an exasperated Hosni Mubarak laid on the table in 2009. Hamas then refused to sign. But Mubarak, who, behind the scenes, co-ordinated his Palestinian policy with Israel, is now an ex-president under investigation for

corruption charges. The interim Egyptian government is less hostile to Hamas' patrons in Iran; seen from Gaza, that makes them a better guarantor.

But the ground is also shaking under Hamas' feet. Its political leaders are based in Damascus and they cannot have failed to notice that even Al-Jazeera has turned against their closest ally, Bashar al-Assad. The impact of the Twitter and Facebook revolution has so far barely been felt on the streets of Ramallah and Gaza, but the leaders of Fatah and Hamas realise by now that there is a limit to how long they can continue ruling their fiefdoms without a renewal of their long-ago expired mandates.

The cornerstone of the agreement is a fixed election date, a year from now, for both parliament and presidency. Meanwhile, a "technocrat's government" will be formed, without overt members of either movement.

It may have been christened a "reconciliation agreement" by the media, but for now it is merely a deal between two separate entities. Neither side will relinquish real control of the West Bank or Gaza, certainly not the chiefs of Hamas' military wing and the Palestinian Authority's security apparatus, both of which are the real power on the streets. They will continue holding sway until the elections, if indeed they are held as scheduled.

And who can foresee what will follow? Much will certainly happen over the next year to shake this fragile treaty.

Israel, meanwhile, has been swift to respond. Within an hour of the Palestinian announcement, Prime Minister Benjamin Netanyahu had prepared a televised statement saying: "The Palestinian Authority must choose either peace with Israel or peace with Hamas. There is no possibility for peace with both. Hamas aspires to destroy Israel and fires rockets at our cities."

Israel's immediate concern is that the agreement will become a back-channel to legitimise Hamas and that it will further bolster the Palestinian Authority's efforts to gain international recognition for an independent Palestinian state, regardless of negotiations with Israel.

But the move could still backfire for Palestinian President Mahmoud Abbas. In recent days, he has become concerned that, despite earlier reports to the contrary, the Obama administration may try to dissuade other western countries from supporting a United Nations resolution in September in favour of an independent state. In an interview last week with Newsweek, Mr Abbas accused the American president of misleading him. "It was Obama who suggested a full settlement freeze," he told the magazine. "I said OK, I accept. We both went up the tree. After that, he came down with a ladder and he removed the ladder and said to me, jump. Three times he did it."

A new relationship with Hamas will certainly make it even harder for Mr Abbas to deal with the Obama administration and the agreement could reflect a strategic decision by the Palestinians to rely less on the Americans, who seem over the past few months to have lost influence in the region.

Mr Netanyahu will try to use his US visit next month to convince his counterparts that the way to regain this influence is not by making more concessions to the Palestinians.

Meanwhile, there could be a few short-term gains for Israel. The large-scale demonstrations being planned by grassroots Palestinian movements for May 15th could lose some of their motivation now that at least one of their main demands - Palestinian unity - has been met. The Authority's security forces will certainly have a bigger interest now in keeping calm and not letting the demonstrations turn into a Third Intifada.

Another possible gain is progress towards a potential prisoner exchange to release Gilad Shalit. One of the main stumbling blocks to a deal has been intra-Palestinian rivalry. Senior figures in the negotiations have blamed Mr Abbas for working hard to scupper any deal rather than allow Hamas to gain credit for releasing hundreds of Palestinian prisoners.

A period of relative calm between the Palestinian factions may finally allow a breakthrough.