it's called Rock in Rio, because it's the same format of the event that happened in Brazil, the same organizers (Roberto Medina, etc.), the same charity goals, and most of all a same brand, because Rock in Rio is becoming a brand.
Furthermore, Rock in Rio, doesn't only mean Rock in Rio de Janeiro.
In portuguese (language not only spoken in Portugal, but also in Brazil) Rio means River. Rock in Rio, means Rock in River.
Like Rio de Janeiro, Lisbon also has a river, the Tagus/Tejo river, and from the Rock in Rio park you have a nice view of it....it's hearing rock with the river in the horizon.
There are plans for 2007 for Rock in Rio to be held simultaneously in Rio de Janeiro, Lisbon and Australia (Sydney, probabily). A new expansion of the Rock in Rio concept and brand.
By the way, the daily tickets for the event cost 53€. That's how much I paid to see Paul McCartney. However on Paul's day he was the only one performing. But on the rest of the days, for the same price you can listen to many bands. Tonight Mettalica, Slipnot, Massive Attack are playing, it's the metal night. On sunday Alicia Keys, Sting, Alejandro Sanz, and other portuguese bands. Tomorrow it's Britney.
The greatest thing you will ever learn is to love and be loved in return.