If the course and course content is free, then certification has to be fee based. The model doesn't work otherwise.

Professors Thrun and Evans have never said certification will be free. MITx has stated that their certification exams will be fee based.

Think ACT, SAT, GRE, GMAT, LSAT, etc.

The certification exam for the course IS the brand. Passing a difficult, no-nonsense, comprehensive exam is certainly suitable for a CV.