this report from Cult of Mac says that there is at least a 15-inch model in the pipeline right now.
This would line up with my previous speculation that the current MacBook design would soon give way to smaller, MacBook Air-like designs.
As shown by Apple's recently updated MacBook Airs, tremendous horsepower is possible in even the thinnest laptop designs. This report shows that the mid-2011 MacBook Airs rival last year's MacBook Pros, which is no easy feat (I happen to type on a 2010 17-inch MacBook Pro now, and it's no slouch).
Current MacBook Pros carry a design that is almost three years old. It's about time for an update. But seeing as how the current design is already the best in its class, it's hard to fathom just what could be dramatically changed or improved. Well, it seems the old adage "thinner and lighter" will just never go away. At some point, making these notebooks thinner will be like trying to split paper.
Pundits are saying we might see these new models sometime this Fall. I'll be getting one, I'm sure. I dont' even have to see it to know.