It's rare for a crowd at a rock venue to fall silent, especially when the headlining band is the booming, horror-movie-inspired lounge outfit Broadcast. But because the band opening for Broadcast was the harmonic, folksy duo Iron and Wine, all bets were off. The people who arrived for the opening act had come, for the most part, specifically for the opening act. The mood was pensive, reflective, autumnal. The crowd huddled near the stage and didn't make a peep -- seriously, you could have heard someone whispering in there. Between acts, in spite of the opening band's encouragement to stay and enjoy the main act, about half of that crowd left, only to be replaced by a slightly more fashion-conscious batch of artsy kids -- you know, disheveled hair, thin belts, low-riding jeans, up-dos. With a big sound and big images projected onto a big onstage movie screen, Broadcast's name didn't lie about what the band would do. People danced like all get-out, reveling in that all-too-rare opportunity to shake it to the sound of a theremin. On the one hand, it was a split-personality show because the crowds were actually different. But then, for the few who stayed all night, it was like getting two nights at the Bottleneck all in one.