By the powers of the underworld, I call this thread up from the dead!!! Arise and live again!
That said, it's an interesting question and one that I have come to admit I am completely unable to answer without bias. I was raised playing poker from a very young age. How young? Think of the youngest age you believe a child could learn poker at.
Younger than that! lol
I had learned poker and was playing for real money (albeit pennies and nickels) before I started attending grade school. I am certain I had memorized the hand rankings before 1st grade and was playing long before that. My grandmother started us playing Razz (7 stud lowball) because we didn't need to remember anything. We played frequently growing up.
Did I learn some of those skills mentioned in the second post? Oh yeah. And I learned the hard way that the money I lost had real value. Even to this day I play very small stakes because my upbringing caused me to respect the value of money and the pain that losing could bring. My family also played with some "ugly" home rules... including open-stakes. And open-stakes develops courage like you've never seen but will experience in the real world. With open-stakes, you are never sure exactly what is at stake... you might have $20 on the table... and your opponent might only have a dollar... but he can reach into his pocket and pull out as much as he wants, whenever he wants. And that's like real life, where you're often not sure how much risk there actually is but you have to make decisions and act on them anyway.
I always had great math skills growing up... but more than "calculation" skills... we (all the children and cousins) developed a profoundly keen "math sense" along with card sense. That is to say, we developed an intuition and a feeling about how numbers most likely related to each other. This is a skill that's very useful in and out of school. With a keen math sense, a student can look at the answer they arrive at (for a multi-step problem) and have a good feeling for whether it's close or not. There were many times in school where I missed a step or miscalculated on a step... and when I arrived at the answer... I could look at it and tell that it wasn't right because it didn't make sense. I can't tell you how many students will do multistep addition and multiplication problems (with whole numbers) and end up with a result that's obviously too small but they have no math sense and can't see it immediately. It's a skill teachers spend a long time teaching but one that develops through experience playing poker.
And, for all the people who worry about kids gambling, and this is where my upbringing probably gives me a skewed worldview but maybe not, you would be shocked at how much gambling kids really do. They "rock-paper-scissor" for snacks at lunch, the flip a coin for the right to pick something first, or any of a number of other things. When two boys flip a coin to see who gets the window seat on the bus... many adults don't see gambling there. But any time something of value is risked on an unknown outcome, you're gambling. The problem is that things of value to children aren't often monetary. Gambling is a natural part of childhood and being human. Keeping children away from poker isn't going to stop them from gambling... it's just going to leave them unprepared and unskilled when it comes to gambling later in life.
As one last note: growing up my cousins and I brought many an unsuspecting friend into the world of poker. Very few resisted... most were eager to play and quickly fell in love... despite being easy prey and horrible at the game. The few children I knew that were not eager to sit in a strange game and play... were all my relatives who had been brought up playing. We'd been instructed our entire lives about the skill aspect of the game, about cheating, about being wary of unknown people, and being willing to lose everything we put into play. Those lessons made us less likely to end up in a game we did not personally control because we were warned (probably too much but that's another point) about the dangers of playing. It was less than a year ago where I had to talk to my step-brother (not raised playing) and pull him aside and convince him to NOT go to a private game. He was eager as a beaver to play a private game with a couple of guys he just met and a $1,000+ buy-in. So much of it rang warning bells in my head but he wasn't thinking twice about it. When I explained my concerns, bankroll and robbery wise, he did wise up and passed on that game until he could find someone to vouch for the guys and the level of the game.
All those parents NOT teaching their children poker and/or at least the skills to recognize a bad situation and bad gamble... are sending them out defenseless to meet up with kids like I was. And the kids like myself are out there... they're arranging spread-limit stud games before church youth group meetings... they're convincing friends to bring Halloween candy over to play cards with... they're eager to "teach" them how to play and will even find a card with all the hand rankings so they know what beats what. They're out there and they're more common than you might think. Growing up, I was in my late teens before I had a peer who didn't end up playing cards with us and wouldn't be talked into it -- and he was Southern Baptist and believed all cards were the Devil's device... so that might have had more to do with it. The kids will play... maybe not as early as I did... but sooner than you might think... and almost always for something of value.. aka, they will be gambling.