President Saleh has been unable to halt the demonstrations. The few attempts at using lethal force have left over 130 dead, and did not, to any noticeable extent, discourage protestors from continuing to come out. So Saleh appears to have accepted an exile deal put together by Saudi Arabia and other Arab Gulf states. Negotiations for this are complex, as they involve details like how much embezzled money Saleh and his cronies can keep. There's also the matter of how many Saleh aides, and their families, will get sanctuary and to what degree, and how much immunity from prosecution for past sins all the exiles will receive.
Then there is the matter of who takes over. There are not a lot of volunteers for this, because the responsibilities are complex, time consuming and dangerous to deal with. Saleh's replacement will be expected to fix more things and help more people than anyone has cash or resources for. Yemen is very poor, and is ruled by successfully keeping the unhappy majority quiet. Moreover, Saleh has been in power 33 years, and his family has monopolized key government jobs for decades. Any new government will start out with inexperienced leadership. No one is looking forward to this. Many Yemenis will expect a lot from a post-Saleh government, but that government will be much less capable, than the current Saleh crew, of delivering.
Then there are the foreign patrons. Saudi Arabia supplies about a billion dollars a year in bribes and "gifts" to buy information, influence and the occasional favor. Most of this goes directly to tribal leaders or senior members of the government. Other Gulf Arab states and the United States supply another billion bucks, most of which goes to the government. Most of the government budget (about $12 billion a year) is from oil exports. That oil will only last another decade. While lots of Yemenis want Saleh gone, very few want to replace him.
The major unrest recently has been in the southern city of Taiz, where three days of large anti-Saleh demonstrations have left at least 18 dead and over 2,000 wounded. The government has to face the fact that it has not got sufficient troops and police to discourage more demonstrations. Firing on the crowds doesn't work either, because so many Yemenis have weapons, and the security forces lose if they get into a general shooting war with the people. So Saleh is looking for a way out, and Yemenis are nervously looking around and wondering what, or who, comes next.