Could this be it (Syzygium paniculatum or australe - note at the bottom of the page there's a suggestion of uncertainty)? Seemingly Syzygium, although Australian, has been grown as a hedge in California and does have opposite leaves.

http://www.smgrowers.com/produ...

@sooby Good eye Sue, Syzygium sure looks like a good possibility!

http://www.anpsa.org.au/s-pan....

http://edis.ifas.ufl.edu/fp567

More photos for comparison:
http://toptropicals.com/catalo...
http://hubpages.com/living/Syz...

Your Florida link mentions topiary, Lin, which also seems to fit given the pictures at the top of the thread.

S paniculatum was originally Eugenia myrtifolia which is what Lin suggested way back at the beginning of this thread.

Showy white flowers borne in the warm months are usually pruned off and not very noticeable, but flowers on unclipped plants are quite attractive as they fill the canopy. Several stems arise from the lower part of the tree, forming a multiple trunked tree well adapted for many landscapes. The plant may still be referred to as Eugenia myrtifolia in some catalogues.