They have used the sling for so long over in palistine that it must be effective for the rioters.

...and good for throwing grenades! Check out the posts on sling as a modern warfare weapon, and fireslings a few weeks back. I think its the perfect weapon: hides anywhere, fast and cheap to make, can throw just about anything one can put or balance in the pouch, used by a horde of untrained people it will still rain lethal fist sized stones onto a crowd...and if needed, can be made from a shoe. What are ther IDF gonna do? Arrest every Arab kid wearing shoes??

Justin

I think an answer to both the question of the effectiveness of slings (particularily those massive stone, long cord ones) and the apparent fewer number of visible slings is that using one is likely to get yourself shot at.

Well the question is: can a sling stone hurt a soldier wearing a kevlar vest with ceramic chestplates?

Remember that we're still talking about rioting, and not about actual city warfare or anything like that. 
About kevlars, I'm no expert, but I still beleive that a high velocity, fist sized sling stone in the chest will hurt, even through a kevlar vest. And if it hits the head, it should at least cause a minor concussion. Unless they are wearing some super helmets that I'm not aware of.
And if the slingstone doesn't hurt through the soldier's armor, then it will certainly hurt if it hits the face, arms, or legs! And since many palestinians have used a sling from their early childhood, I'd assume they're quite accurate with those things, making them able to aim at the most vulnerable spots.

I'm glad I live someplace where nobody's trying to kill me.  None of my targets shoot back!

Well, that's just it.  I see these palistinian slingers all the time and I assume that they are fairly experienced with the weapon.  But I've not read any reports of Israeli soldiers being killed by a slingstone. 

On a sidenote, I was reading about the Roman conquest of Britain.  Of particular interest was the description of the Roman sackings of a string of hilltop fortresses manned by thousands of slingers.  Now according to history, none of these fortresses took more than 1-2 days of seige to conquor.  Of course by that time(1st century ad), legionaires themselves had stopped training with the slings.  So I'm wondering, if thousands of experienced slingers using lead projectiles with the advantage of elevation would fall to a relatively small force of Romans so quickly, then maybe the sling isn't as effective as the ancients say it is.