Obama went to Harvard, not Yale. Skull and Bones is strictly a Yale fraternity. Hence, Obama clearly isn't Skull and Bones.
One might be a member of both fraternities, but not necessarily. Freemasonry has very high standards for selecting members. Within the fraternity there are no "legacy" memberships, each man must freely ask for admittance to our order, be recommended by members in good standing, and pass a background investigation. A home visit is made to the applicant to meet and talk with his family. Felons and those with serious mental/emotional problems are excluded. A man's reputation and honor must be unsullied and clean. The Lodge will vote on whether to accept a candidate, and a single black ball is enough to deny membership. Once accepted as a candidate, the applicant will be put though a lengthy period where he will be working with a mentor very closely to learn certain elements of our craft. No member, or candidate for membership is ever asked to do anything that would bring dishonor, discredit. or embarrassment to himself, his family, community or nation. We do not haze candidates, but work assist a man in becoming better for himself, his family and country. The process is intense and uncompromising, and for that reason when we meet a fellow Mason anywhere and anytime, we know that we are dealing with a man who can be trusted implicitly.
Many of the nation's Presidents have been Masons and among the Founding Fathers, Washington and Franklin were only two of the most illustrious members of our order. I do not know if Sen. McCain or his father, or grandfather were Masons, but wouldn't be surprised if they were. Masonic membership has not been uncommon amongst US military men, especially within the officer corps. Many distinguished men from all walks of life have been members, and membership isn't secret. Masons are at the forefront of many community betterment efforts. We support hospitals, orphanages, rest homes for the aged and disabled, and many other charitable efforts.
It is quite true that our membership has declined, and the average age of our membership is getting older every year. This is true of most fraternal organizations these days, since young men are no longer drawn to "joining" with others in formal fraternal organizations. Earlier in this thread someone said that in New England, Freemasons are advertising for members. Wow! That's news to me, just a little bit shocking, and I'm not sure many Masons will approve of the idea. I rather doubt that will become an accepted practice with Grand Lodges elsewhere.
BTW, My father, grandfather, and several great grandfathers were Masons. On the other hand neither of my sons has shown any interest in joining. It would please me if they did, but it would be improper to urge it upon them. If they come to see the value of becoming Masons, I'll be the first to sign their applications.