There are rumors that Apple is working on redesigning the MacBook Air. Apple is aiming a complete revamp to all of their notebook lines sometime this year. The MacBook Pros would be discontinued and the the new ones would be in the style of the Air with a super thin design, no optical rives, and centered around portability.
These rumors are driven by word from overseas suppliers. The MacBook Air style notebooks would have a 15 inch screen. This move would be slightly controversial because a lot of people still like having DVD burners built into their laptop. I would take this new with skepticism because after all, it is just a rumor.