This could be very significant. You have to know something about Israeli politics to understand this, but in short, there are so many parties in the Knesset that no one has ever gotten a majority--all governments are by coalition. Sharon has a coalition with several parties which are ideologically opposed to a Palestinian state. If moves are made in that direction they may bolt the government, causing new elections. However, if Labor joins in their stead, this means Sharon will have a huge working majority which can pretty much do what it likes. This gives Sharon a lot more breathing room then he would seem to have at first glance. In other words, by one of the typical twists of Israeli politics, Labor and Sharon are now eachother's best friends. They are his leverage over the Right wing parties, he is their possible ticket back to power.