Fears that Syria is using them to retain some sort of grip on the country have been exacerbated by international pressure to implement UN resolution 1559, which calls for all non-government factions to lay down their guns.
But behind the high politics lies another, more human story.
Palestinian community leaders and NGO workers say that the real danger comes
from the deplorable conditions in which the country's 400,000 Palestinians - refugees since the establishment of Israel in 1948 - continue to live.
They argue that deteriorating services in the 12 cramped refugee camps and the lack of future prospects for the young are fomenting the conditions for extremism.
Sylvia Haddad, one of the Palestinian elite with Lebanese citizenship, runs the charity Joint Christian Committee (JCC), which provides refugees with training.
"Now there is no more ambition in the camps," she says. "They say, 'even if we study, we can't work'. Their big dream is to buy their cigarettes. This is very disturbing for us as Palestinian leaders."
The malaise means that her projects are suffering.
"I have the funding, I have the teachers, I have the equipment. I have everything. But I don't have the beneficiaries," she says.
"The Islamic groups are moving in. We - the NGOs - are moving out."
Part of the problem is the restrictions placed by the Lebanese government on Palestinians' right to work, barring them from over 70 professions.
In August, it lifted the ban on 50 jobs, although the professions - law, medicine, engineering - remain off-limits.
But Palestinians say that, with a work permit costing hundreds of dollars, the change has had no impact.
"Nothing happened. No Palestinian has benefited from this rule," says Hasan Bakir, a Palestinian journalist for al-Quds newspaper.
In the heart of Shatila refugee camp, locals have domestic worries, too.
Every winter, residents in the southern end of the camp find their homes flooded as the over-worked water and sewage system fails to cope.
"Every year we are afraid of the water!" says Nadia Abdeen, resident of a ground-floor flat, describing how she threw away her contaminated furniture after the flood subsided.
"Not only the seats - the carpets, clothes, beds."
Like others in the camp, she has been feeling the effects of the funding crisis that has hit the United Nations Relief and Works Agency (Unrwa), which is charged with providing Palestinian refugees with services.
"All the people go to Unrwa, but they don't do anything," says Ms Abdeen.
Dreams of escape
Palestinian refugees draw little consolation from explanations that it is the growing population and rising healthcare costs, rather than cuts, that have led to poorer services.
"The needs are growing, but the budget is not growing at the same pace," says Hoda Souaiby, Unrwa's public information officer in Lebanon.
Other sections of Lebanon's Palestinian population have even fewer resources to draw on.
Fatima Kayed lives in Qasmieh in south Lebanon, one of many illegal "collections", or encampments scattered across the country.
She and her six children live in a makeshift home largely constructed of corrugated iron. "In winter, the water gets under and it is cold," she tells me.
Social worker Hannan Hassan, who runs a youth club in Qasmieh for the French charity Enfants Refugies du Monde, says that many young people dream of a better life abroad.
"There is no chance for the Palestinians to work, because if they get an engineering or a law degree - what is next? So they plan to work abroad - maybe illegally."
Her brother fell victim to a common scam, paying $2,000 - his life savings - for the prospect of emigration to Germany.
"This man asked him to visit his office in Beirut, but when I tried to go, I found it was a false address," she says.
Recently, NGOs have begun to highlight the plight of the "non-IDs", a group of Palestinians lacking identity papers who are not recognised by the Lebanese government or Unrwa.
They risk imprisonment if they are caught by the authorities, and survive on the black economy - or cash from political groups.
Mohammad al-Najjar, project co-ordinator for the Palestinian Human Rights Organisation, is campaigning for them to be officially recognised.
"We, as Palestinians, are worried about it. Of course, they will be very dangerous if the PLO stops the funding, and the situation is as it is now," he says.
"There are four to five thousand of them, and they are still young."
He warns that they, as much as anyone, might be the force that upsets Lebanon's delicate sectarian balance.
"If you put them in a corner, what can they do? They will replace the earth with paradise."