neat picture; kind of looks like an alien squid.

did you happen to take pix of the tree leaves? that might make it easier to ID.

Are açaí berries found wild in Hawaii?

I' not sure if they are. Edible fruit does grow on the Aihulama trail for sure though because I saw guava fruit. I didn' take a picture of the leaves unfortunately. If they are acai I'd want to take a few to attempt to grown my own

not acai. the color of the 'tentacles' where the fruits are attached are a light brown/white color on acai palms. acai is also a clumping palm, so did you notice multiple trunks coming out of a single root system? also acai is a tall palm (60+ feet) so it wouldnt fruit until its well overhead. it does have a slender trunk though like the photo. and finally to truly identify palms youll need to look at the leaves aswell as the fruit and fruit clusters.

beautiful palm though

you might get an better answer on the palms forum http://forums.gardenweb.com/forums/palms