The mayor of Rio de Janeiro, Eduardo Paes, paraded in the baterias of three samba schools in Rio Carnival 2011. He played to the three schools affected by the big fire in the City of Samba, Grande Rio, Uniao da Ilha and Portela. These schools have been made exempt from the competition this year. He explained that this way he couldn't prejudice anyone's marks, I saw him on Agogo in Portela and chocalho in Grande Rio and Ilha. He is not new to samba school parades; as a fan of Portela he has paraded in the sambadrome already, but I don't know if it was in the bateria.
The big parades of the major samba shools of Rio de Janeiro are all viewable on youtube. These days youtube is also showing the more precarious parades of the lower groups in years gone by, and some of these are amazing, for all the wrong reasons. There have been schools that have had to parade without any drummers. Here's Unidos de Campinho, parading in the sambodromo in 1992.
http://il.youtube.com/watch?v=zkkj1gRkSjY
In fact, the drummers were there, but the lorry carrying the instruments hadn't arrived. The bateria (drummers AND drums) is such an important part of the parade that it has its own separate judges. No drums, no marks. The commentary tells us that the instruments turned up eventually, but right till the end of this clip there are no drums to power the dancers, just a cavaquinho and a singer. A particular shame as the song itself was lovely that year. You can see all of the dancers doing their best to participate with energy, but it must have been hard.
This sort of thing tends to happen to samba schools in severe financial and organisational trouble. The following year Unidos do Campinho failed to parade at all due to financial problems, and soon the samba school was completely disbanded.
The video commentator tells us that it happened once to Mocidade Independente do Padre Miguel, when the bateria was being led by the great Mestre Andre. The truck carrying the drums suffered an accident on the way to the parade ground in the Rio Branco. Alternative transport couldn't be organised in time. But Mocidade Independente have continued on to be one of the great samba schools of the special group in today's Rio carnival.
Tickets for Rio Carnival 2010
Tickets are going on sale in the next couple of weeks. They will all be sold out in minutes, mostly to Cariocas (Rio locals) and agencies. As a tourist you are very unlikely to buy at these original face prices. Expect to buy from an agency with a mark-up of at least three times the face value. Its already possible to reserve tickets for the sambodromo through online agencies.
Original face values:( R$ = Brazilian Reals);Frisas (for 6 people) from R$3000 to R$6,500 per night, Arquibancadas (stands or bleachers)- from R$110 to R$300 per night per seat.
If you get the opportunity, here's how to get the very best out of your experience.

You can buy a tourist package for Rio Carnival that includes parading with a Samba School. You can also organise it yourself (advice below). Either way, if you want to know how to get the most out of this once in a lifetime experience, here's how to go about it.
Beija Flor is planning a 67meter long float for Rio Carnival 2010!
Rio Carnival floats are already gigantic. Up to 30 meters long, they often have problems getting under the motorway flyover outside the Sambadromo. Sometimes floats get stuck trying to get round the right angled corner at the beginning of the sambodromo. Just one stuck float can create a gap in the parade that can prevent a samba school from winning the carnaval, the culmination of an entire years work.
Mangueira has also announced plans for a float over 60m long. There's no way that a 67m float can get round the corner, so there must be some clever engineering solutions planned. Will it be constructed like a train, or a caterpillar, with different segments joined together? Will there be a main part and then outlying bits connected by costume or theme?