DefenseLink News Release:
The RFP stipulates nine primary key performance parameters: air refueling capability, fuel offload and range at least as great as the KC-135, compliant communication, navigation, surveillance/air traffic management equipage, airlift capability, ability to take on fuel while airborne, sufficient force protection measures, ability to network into the information available in the battle space, survivability measures and provisioning for a multi-point refueling system to support Navy and allied aircraft.
Payton stressed that the department has gone through a rigorous review process for KC-X and has validated that the RFP accurately reflects the requirements as laid out by the warfighter.
The final RFP defines an integrated, capability-based, best-value approach. It includes specific factors for assessing the capability contribution of each offeror. Along with cost and assessments of past performance and proposal risk, these factors provide the source selection authority with excellent means to determine the best value between proposals of significantly differing capabilities and cost.
All sorts of documents are available here.
UPDATE: More at Strategy Page: KC-135, KC-767, KC-30 or KC-777?
UPDATE 2: Good summary found in the comments: Air Force tanker request gives Boeing edge, for now