You can go to Itacaré by plane, but the airport its in the city of Ilhéus, where you have to take a bus (US$3,5) or a taxi (US$45) to go to Itacaré. Or you can come by bus from Salvador (5 hours). The roads are in a good situation.
To go to the beaches aroud Itacaré (there are many!) you can take the same bus towards Ilhéus and order the driver to stop the bus next to the beach that you want to go. Try to speak a bit of portuguese because they dont speak english.
The nearest airport to Itacare is Ilheus and the closest international airport is in Salvador. There are daily flies to Ilheus from Salvador, Porto Seguro, Belo Horizonte and Sao Paulo by Brazilian companies GOL (http://www.voegol.com.br/INT/) , TAM (http://www.tam.com.br/b2c/jsp/default.jhtml) and BRA (http://www.voebra.com.br/).
To get to Itacare you will most probably need to connect through Itabuna or Ilheus. Rota has hourly buses to Itacare from Itabuna (2,5 hours) and from Ilheus (1,5 hours).
Coming from the north you can avoid Ilheus and save 130 km. You stop in Ubaitaba and change to Itacare via Taboquinhas. Unfortunately the road is in a very bad condition but the scenary is beautiful.
There are also two weekly buses directly from Salvador. The journey takes about 8 hours.
Another options is for those who comes from Morro de Sao Paulo, Camamu and Barra Grande. You need to come to the south of peninsula Marau where you cross the river Contas by a little ferry. This trip can be organized by travel agencies which make tours from Itacare to peninsula Marau or Barra Grande.
From the rodoviaria in Itacare there are frequent buses to Ilheus and Ubaitaba. To Ilheus it is only about 90 minutes and there you have connections to many larger cities. Ilheus is a 6 hour bus ride from Salvador da Bahia, there are 3 executivos per day, one of them is a night bus departing around 10pm. There is also a Leito (deluxe night bus) from Ilheus to Salvador.
Fly into Illeaus and its a short bus ride. If you fly into Salvador its a 7 hr bus ride to Illeaus, then a 40min ride to Itacare.
The final bus into the town makes quite a few stops, but the fact that everyone seems to know each other around these parts makes for an interesting ride.