from an email I received:

Ben & Jerry's wants to thank you for voting by giving you a free scoop of ice cream! Come to participating scoop shops on November 4th!

From 5-8pm, show us you voted and you'll get a free scoop of ice cream. Show us your "I Voted"
sticker, a photo of you in front of your polling station, do the "I Voted dance" or just tell us you voted.