Technopathy can rewire electronic gambling machines and cheat that way, hypercharm can bluff their way out of anything with Lie, illusion powers/powerful psychics can make you think that someone's got a full house, Mindreaders can see what the man across from them is holding... Yeah, there are a few ways to do it.
Couple others off the top of my head would be speedsters swapping cards faster than you can see, someone who is telekinetic or has a strange noodly appendage (Londo in Babylon 5) can hold a hidden card somewhere no one will find it, or a hypermind might count cards to verify exact probabilities of the current hand.
We need a main Wild Talents thread, I think.