According to the official calendar, the 2010 carnival will take place between 12 and 16 February. The Rio de Janeiro escolas de samba will parade at the sambadrome on Sunday 14 and Monday 15. The São Paulo parades will take place on Friday 13 and Saturday 14.
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.