Got this mailer this week (see attachment). Xfinity Performance Internet with download up to 15Mbps for $19.99 for 12 months with a 1 year contract. Have to call 1-855-611-9966. Just signed up yesterday without any issues. Just told them got a mailer and did not have to provide a code or anything. Offer for new customers only end 7/29/2012.
They also have Blast Plus for $49.99 for 6 months with speeds up to 25 Mbps.
Edit: I am in the Washington DC Metro Area.