Well it seems I have poked a hornet's nest with this one...
I guess I shall have to polish my rhetorical prowess...
I think it would be cool to have a poker club, like a chess club. If you keep it extracurricular, and only allow it for students old enough, like at the least 8th grade and above, I think it would be a pretty cool way to get students more interested in their overall study and performance in their classes. But not as an actual class itself.
But you still have the problem of whether or not poker would encourage students to get into gambling. It is just hard, maybe impossible, to separate gambling from poker, and I don't know if the potential positives for students would outweigh the potential negatives.