Yes, some sort of Tillandsia, difficult to say when they are not in flower. If not deliberately placed there some time, they often grow from air-borne seed.

There are more than a dozen native species in Florida, plus one non-native.

http://bonap.net/NAPA/TaxonMaps/Genus/County/Tillandsia

Most likely Tillandsia recurvata, commonly called "ball moss". Extremely common on Quercus virginiana and other hardwoods in the deep south.