Please note: Somerville MA is where Jr lived while he was a student at Harvard. During that time he amassed over $400 worth of traffic tickets which were paid off in Jan/07 before he announced he would run for the Presidency!
It means nothing, except that there is a record of Obama from some database (possibly court records, as per the tickets), in Somerville.
I wouldn’t type my name and birthdate into anything on the net like the site linked above.
I think the information that came up is most likely because he lived in MA for a while. I would not trust it as the name of the city where he was born.
I will believe he was born in Hawaii until further notice and his original birth certificate comes out from under seal if it ever does. It is not really needed to show that he is not a “natural born” citizen. He is most likely a citizen, but just not “natural born”.