What we've done in the Windows installation is bundle a minimal JRE as a light-weight library. The JRE is loaded by AeroFS at runtime and is otherwise completely isolated, so no dependency exists on Java in Windows. Based on how well that has worked out so far, we'd like to do a similar approach for OSX and Linux soon.
Damn, so back to AeroFS? :) I was quite happy with the syncing (although sometimes the sync started after a long time), but I decided to dump java from my system..
Do you have ETA for os X and Linux of this "java free" versions?