I meant to post this in time to commemorate the 25th April.
Marius70 has put together a very comprehensive collection of songs from the Carnation Revolution. Holding red carnations, the Portuguese people persuaded the military not to shoot. Very moving and beautiful.
Music played an important part in the uprising. (from Wiki) There were two secret signals for the start of the military coup: first the airing of the song "E depois do adeus" by Paulo de Carvalho, Portugal's entry in the 6th of April 1974 Eurovision Song Contest, which alerted the rebel captains and soldiers to begin the coup. Next, on April 25, 1974 at 12:15 am, the national radio broadcast GrÃ¢ndola, Vila Morena, a song by Zeca Afonso, a progressive folk singer forbidden on Portuguese radio at the time. This was the signal that the MFA gave to take over strategic points of power in the country and "announced" that the revolution had started and nothing would stop it except "the possibility of a regime's repression".