The box office data at this time of year usually doesn’t tell us much, but last weekend was an exception. Reese Witherspoon is a star. “Barbershop” has legs. And “My Big Fat Greek Wedding” is still taking in $10 million a weekend!It’s not news that “Greek Wedding” is a sleeper. But as it now drifts toward $150 million worldwide, it is clear it is also a major blockbuster. Perhaps the cheapest blockbuster ever, as well as the top-grossing indie hit. The runaway success of “Greek Wedding” tells us several things: It’s a reminder that “people pictures” still resonate with the audience. With a cluster of pricey sequels and franchise movies about to rain down upon us, this is an important reminder. Its success also underscores the resilience of the independent market. People may pontificate about the problems of this sector, the difficulties with financing, the clutter in the marketplace, but these factors didn’t inhibit “Greek Wedding.” Sure, the movie may not represent “high art.” It wouldn’t win a festival award. It may not get an Oscar. But it nonetheless is a reminder of a lasting rule of showmanship. In a world of $50 million ad campaigns promoting $150 million movies, “word of mouth” is still the best marketing tool ever devised.