Tripleshot, every single block you turn in is a vote for your chosen charity. You pick one when you set up your d.net account. You can change you mind whenever you want. Just edit your profile from your stats page.
As far as the $1,000 that would be given to the winning team, Anand said it would go to a national charity. I can't remember which one, but it's not just a local chapter. I think it was to help battered women and children, but don't quote me on that.
It's up to the individual that finds the winning key to decide what to do with the $1,000. There have been many ideas about building a team crack rack, giving it back to d.net, etc...
Hope this helps.