"The license granted hereunder will terminate, automatically and without notice, for anyone that makes any claim (including by filing any lawsuit, assertion or other action) alleging ... (b) that any right in any patent claim of Facebook is invalid or unenforceable."

(the entire rest of the ... is clause (a))

Oops, not sure how I misread that, it's pretty clear! This unfortunately seems to reduce these projects in usefulness to pretty much awesome and interesting research - completely unusable in any business though. I don't see how any business can be expected to make all employees keep to these conditions - way too fragile and easy for an employee to screw the company.