I've noticed that the page in portuguese has a lot of information, but I can't trust my english to edit the main page directly. So, I will try to put some translations here, and somebody with more fluent english can rewrite it.
History of Florianópolis: the city was established in 1726. The original name of the city was "Desterro" but it was changed in 1894, in honor of Floriano Peixoto - the Brazilian president at the time.
Places to go:
Naufragados Beach, on the south of the Island. You need a guide, because there are no roads leading there. A half hour walk along a trail (trekking)through the forest gets you to the beach. It's very beautiful and I have some pictures that I can post.
Anhatomirim, a small island with an ancient fortress (built on 1793) and a lot of stories.
Praça XV de Novembro, that has an ancient (more than 100 years) ficus (not sure about this word)tree.