The frequent flier blitzkrieg continues. This week's stop, Sydney, Australia for SMX. In the opening keynote, Danny Sullivan asked Google's Marissa Mayer what keeps her at Google. Her answer was that there are just too many really interesting, really hard questions still to be answered. She likened it to the world of scientific discovery and pegged the current state of search and online as analogous to the 15th or 16th century. Sir Isaac Newton has just discovered gravity.