According to the official calendar, the 2011 carnival will take place between 5 and 8 March. The Rio de Janeiro escolas de samba will parade at the sambadrome on Sunday 6 and Monday 7. The São Paulo parades will take place on Friday 4 and Saturday 5.
Although the dates seem miles away, the farsighted travellers will make accommodation arrangements for the period long in advance – it is the only way of finding good value accommodation for places like Rio or Salvador.
As more details emerge I will keep you posted.