Did you hear the one about the actor and the poker champ?  Actually, it's no joke: Don Cheadle and Annie Duke have raised some $2.5 million for Darfur over the last few years with celebrity poker tournaments.  Their charity, Ante Up For Africa, brings together stars from the worlds of showbiz, sports, and poker to have a lot of fun - and raise a lot of money and awareness.  Their latest event is this Thursday in California.

"People really underestimate the generosity of the poker community," says Duke, who's also raised millions for Children's Hospital Boston and other causes.  "It's filled with people who are really committed to giving back and using whatever resources they have in order to improve the world."

Cheadle, who received an Oscar nomination for "Hotel Rwanda" and saw the devastation in Darfur first-hand when he traveled there with a Congressional delegation, is serious about helping the war-torn region - and about poker.  He protested only mildly as Duke described to me how Cheadle took down superstar Phil Ivey at the 2007 NBC National Heads-Up Poker Championship.  And he's not the only celeb intent on the game: Casey Affleck, one of the big winners at last year's Ante Up For Africa event, is back this year, and his big brother Ben has qualified for some high-profile tournaments.

Winners at the Ante Up For Africa events generally donate most or all of their winnings to the cause, but Cheadle says the tournaments are also about building awareness: "Money is obviously extremely important; it's an effective tool to get things accomplished.  But in the end, awareness is what really matters, because we all know that the lasting solutions to these problems are actually political solutions, and you don't get political solutions without the people that are electing those governments caring about the issues."

I asked whether it wasn't an odd pairing: well-off celebs having fun around a poker table in the name of desperate people forced to flee their villages half a world away. Duke pointed out that the events encourage people to stay involved, increasing the money and awareness raised.  "Everybody wants to give, but they also want value in return for their time," she told me.  "I'm not sure anything is more effective than a poker tournament, because people come and they can genuinely hang out with celebrities and some of the famous poker players, and just have a really fanstastic time while they're giving."

Say what you like about celebs' motivations for how they use the spotlight - and I'm sure many of you will, in the comments - but it's hard to argue with results.  And Cheadle is accustomed to taking flack for using his celebrity for good causes.

"Some people look at that and are cynical about it, and think that it's just frivolous celebrities trying to give themselves some sort of gravitas sometimes," he told me.  "But I still say, even if it is that, there is still something going on over there, and we want you to look over there.  So you try and take the opportunity whenever you can."