So, if flammable and inflammable are synonyms, doesn’t it stand to reason that famous and infamous would mean the same thing? That might be the thinking behind this usage on the Yahoo! front page:
Whatever the thinking (assuming there was any), it’s wrong. Infamous means “having an exceedingly bad reputation, notorious, or heinous.” It doesn’t not mean “widely or well known.”
I might say that Yahoo! writers are infamous for their misuse of that word, but that would be wrong, too. They’re just very, very inept at finding the right word.