In a nutshell, if you sign up for the i'm Initiative, Microsoft donates money to a social cause every time you send an e-mail with Windows Live Hotmail or an IM with Windows Live Messenger. The more you e-mail or IM, they more they give. The more people e-mailing and IMing, the more and more Microsoft gives.
That's the nutshell. Here's the nut.
1) Where does the money come from?
It's free for all of us users. The money comes from ad revenue. If you take a look at the products, you'll see little ads there. See? Ads. If you join the i'm Initiative, you're telling Microsoft, "I saw your ad. Now it's your turn." The i'm Initiative is a full-throttle, advertising-supported giving machine. Which should also shed light on some of the other, deeper questions I've been getting. Stuff about life, identity, mission, purpose, and the nature of digital existence.
2) How often do they give?
Every time you hit "send." Send an e-mail? Donation. Send an IM? Donation. Smiley face, smiley face, smiley face? Donation, donation, donation.
3) For more information:
Check out im.live.com. They've got all the information there. Also, I'm going to re-post the video I did with my buddy Ed that lays it out straight. OK, semi-straight.