Starbucks and AT&T have announced plans to offer AT&T Wi-Fi service at more than 7,000 company-operated Starbucks locations in the U.S. The partnership will result in a mix of free and paid Wi-Fi services at Starbucks stores, including two free hours of Wi-Fi access per day for Starbucks Card holders. Starbucks Cards are the company’s refillable gift cards, which are available in various denominations, and cost nothing except for the…