He, supposedly, provided a scanned image of a Certification of Live Birth, and there is some evidence that the image was altered after being scanned in. That Certification is an abstract of information contained on the original Certificate of Live Birth, but not directly obtained from it. Rather from a computer database containing that abstracted information.
And all that it would take to end all of this is access being granted to the actual original, not an abstract, and that is where this ends one way or another.
When I bothered to follow this, the HI original birth certificate was a multi page document back in the 60’s.
The original can be examined in cases of fraud:
http://www.theabsurdreport.com/2008/hawaii-legal-basis-test-error-or-fraud-obama-birth-certificate/
HI Governor sealing Obama birth record:
http://www.freerepublic.com/focus/f-news/2116426/posts
Now one can say that one is satisfied in what has been released so far, others demand more proof, and that is the camp I find myself in, Obama or a family member can release the original at any time and end this line of doubt.