The Washington Post has featured a short video by Travis Fox on the gatherings following Benazir Bhutto's assassination in December.
Her assassination hasn't only caused enormous havoc on internal Pakistani politics, but it also created considerable resentment between the dominant Punjabis and the remaining tribal and ethnic minorities. Many Sindhis (like Benazir) believe that she wasn't assassinated because she opposed extremism and advocated democracy, but that she was killed because she was a Sindhi.
According to the Washington Post: "Few believe the country is in imminent danger of fracturing again. But Bhutto's death has exacerbated ethnic tension in at least two ways: It has angered non-Punjabis because of her status as a member of a minority, and it has eliminated one of the few Pakistani politicians whose reputation transcended ethnicity."
As Gust Avrakotos (played by Philip Seymour Hoffman in the excellent movie Charlie Wilson's War) says: "We shall see".