All over. Really. My church is in coffee shops, lofts, cubicles, living rooms, skate decks, metro benches; Jerusalem, Bombay, Portland (both of 'em); Celtic monasteries, Dutch schooners, Carthaginian markets, Ethiopian royal courtyards...among other places including Salem, MA. It's been said before, but we easily forget: "church" is people, long before and long after it's a building where those people gather. It's something true even if it's hard to get our minds around (hard even for the people who are the church).
A place that hosts people gathered in the fellowship of God—anywhere at any time—becomes a "thin place" between this present reality and the New Creation that's on the way. Those "thin places" are in village houses in Uganda and high-rise flats in Beijing, around tables at Panera and the break rooms on the warf. Any gathering of people in Jesus' name becomes a thin place, thick with value because it's a crossroads of persons in communion with God and with each other.