MexicoReporter on the LATimes Blog produced a film for the LATimes blog here in Mexico City this week about the celebrations surrounding Dia de la Virgen.
See the post and movie here:

Every year, on the north side of Mexico City, a remarkable sight begins to materialize around mid-December. Thousands of worshippers of the Virgen de Guadalupe converge on the Basilica named for her, an oasis of calm and spiritual contemplation in the heart of this restless metropolis.