This info came from a restaurant casual dining email:

— the tweet-a-coffee program. U.S. customers can now sync their Starbucks accounts to their Twitter accounts and tweet to @tweetacoffee and the Twitter handle of a gift recipient. They can then send the recipient a $5 digital eGift.

Through Nov. 6, the first 100,000 customers who tweet a coffee using a Visa card will receive a $5 Starbucks Card e-gift for themselves, courtesy of Visa and Starbucks.