I thought that the purpose of Anaconda was to cordon off the area so as not to allow any of the "rebels" (and what's up with that word, anyway? They're not "rebels"--they're colonial oppressors and terrorists) escape.

So why are we hearing news reports about some of them escaping?

Because nothing's perfect. It's too big an area and there are too few men to ensure that all the al-Qaeda fighters are captured. Way of the world.

Try to imagine if Iwo Jima was the size of Utah. And try to imagine that this is war, not a video game.

The size of Utah? Methinks you exaggerate.

They were talking about a six by ten mile area, in the snow. That gives a perimeter of about thirty miles. I would think that with Predator, or helicopter patrols, they ought to be able to pick up anyone trying to get out, unless they could tunnel behind the lines.

No not Utah but more like New Jersey. As prior military and a historian that reads about the British Empire and the "Northwest Frontier". I can say that war at that altitude and terrain is very difficult and no siege in history has been impervious to stragglers slipping through lines even Cannae had survivors.

http://history.boisestate.edu/westciv/punicwar/09.htm
http://call.army.mil/fmso/fmsopubs/issues/mountain.htm

Look, high ranking Nazi's were able to leave a bunker in Berlin with the Red Army swarming all over the city. A Japanese soldier held out in the Philippines until the 80?s. Punks rob liquor stores and slip by cops. You cannot ensure that you will get 100% of the people you go after 100% of the time.

There's a huge difference between people trying to escape over open terrain, and mixing in with a city population. This is a completely spurious comparison.

My point is that the operation was advertised (at least in the media--maybe they misinterpreted what they were told by the Pentagon) as not repeating the mistake at Tora Bora--that they were going to completely encircle the area and prevent escape. If they weren't capable of doing that, they shouldn't have created the expectation.

There's a book called Blood On The Shore, a memoir of a WWII Soviet naval infantryman and his battles with the Germans above the Arctic Circle. In one incident he relates how he and some fellows managed to evacuate a bare rocky position under fire without being detected.
The point is that even nowadays war is murkier and more chaotic--and harder!--than noncombatants (which include me, btw) can easily grasp.

Also, it's a good idea to listen to Pentagon briefings rather than reportage of those briefings. We're all familiar with the reductionist tendencies of the national news media. A thirty minute briefing loses a lot of nuance when it's mauled into a four-word headline, or a ten-second broadcast segment.

While the Soviets were only blocks away, there was not any large population to mix with. In addition, the Japanese troopers managed to remain undiscovered in a rural not urban setting. Take a breath, Rand if your kid spills his milk, do you hit him in the head? You sound like you have something against the military.
My point was that in these types of operations, you could never guarantee that you would get all the people you go over. Anyone who stood up and said anything like that never had any military training or cannot logically understand the problem. Most people of average intelligence know and understand that while the media seems not to grasp the concept.