http://www.wisegeek.com/what-is-cranioplasty.htm
It’s as if his skull has been opened up for surgery -brain tumor, injury, deformity?
Where are his health records?
This Photo seems to show the scar continues down Obama's neck. (AP can't post)
I would think either a neurosurgeon or someone who assists in neurosurgery or post-op care would be able to say if this looks like a typical cranial incision/cut line.
Does it appear on any more pictures of him?
Here are Obama’s released medical records — a note from his doctor.
http://www.nytimes.com/images/promos/politics/blog/Obama_Health_Summary_letter.pdf
More transparency.