A myth is a story that is most likely entirely fiction. A legend is a story that is based on actual events. Every once in a great while, a myth can inspire an action that itself becomes legend.
You've seen chain letters, piling up in your inbox while the spam filters debate whether it's legit or not. "Send $5 to the person at the top of this list, add your name to the bottom of the list, forward to everyone you know, and get rich overnight!"
You've probably also seen or heard of various forms of the "Bill Gates will pay you to forward this message" chain letter that started making the rounds in the mid 90's. "Forward this message to your friends so that we can test our email tracking system, and I'll pay you money." It was of course total nonsense, but my, how it got the tongues wagging, just for the possibility that it might be true. Everyone knew about it, even if they didn't have an email account!
The Windows Live Messenger team has launched a promotional campaign, the I'M Initiative, in which your use of instant messaging directly benefits the charitable cause of your choice. If you add a special code to your IM name, then each time you start an instant messaging chat with a friend a portion of the advertising revenue goes to charity. It's a noble twist on the chain-letter idea and a remarkable application of word-of-mouth "viral" marketing. Instead of personal greed, compassion and social conscience. Instead of you being paid, you can direct aid to those who need it most.
You IM your friends, and others benefit. You tell your friends about the I'M campaign, and they tell their friends, and your small effort to make the world a better place is multiplied a thousand fold. And if a few of your friends switch to using Windows Live Messenger, hey! Microsoft benefits a little, too. ;>
I doubt the mythical Bill Gates chain letter actually had anything to do with the creation of this campaign, but it does make for some interesting correlation speculation. The tongues are wagging pretty strongly already, and the campaign is just hours old.
You can't help but wonder at life, inspired by myth, becoming legend.