In the midst of the massive geek Mecca that is San Diego Comic-Con, the big Marvel Studios movie panel had all the theater of a presidential campaign rally. Tom Hiddleston appeared in costume as Loki, the bad guy from Thor, and rallied the crowd in character. Then: so many movie stars, including the full casts of the upcoming Captain America sequel and Guardians of the Galaxy. And just when it seemed like it was over, Joss Whedon, patron saint of nerds, walked out for a Steve Jobsian one-more-thing and introduced the first teaser for The Avengers sequel. Eight thousand fans, some of whom had been waiting in line since the night before, shrieked like their souls were being ripped from their bodies.